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Part I - Physiological Colours

Part I - Physiological Colours

1
We naturally place these colours first, because they belong altogether, or in a great degree, to the subject1 to the eye itself. They are the foundation of the whole doctrine, and open to our view the chromatic harmonyα on which so much difference of opinion has existed. They have been hitherto looked upon as extrinsic and casual, as illusion and infirmity: their appearances have been known from ancient date; but, as they were too evanescent to be arrested, they were banished into the region of phantoms, and under this idea have been very variously described.
2
Thus they are called colores adventicii by Boyle; imaginarii and phantastici by Rizetti; by Buffon, couleurs accidentelles; by Scherfer, scheinfarben (apparent colours); ocular illusions and deceptions of sight by many; by Hamberger, vitia fugitiva; by Darwin, ocular spectra.
3
We have called them physiological because they belong to the eye in a healthy state; because we consider them as the necessary conditions of vision; the lively alternating action of which, with reference to external objects and a principle within it, is thus plainly indicated.
4
To these we subjoin the pathological colours, which, like all deviations from a constant law, afford a more complete insight into the nature of the physiological colours.
I. Effects of Light and Darkness on the Eye
5
The retina, after being acted upon by light or darkness, is found to be in two different states, which are entirely opposed to each other.
6
If we keep the eyes open in a totally dark place, a certain sense of privation is experienced. The organ is abandoned to itself; it retires into itself. That stimulating and grateful contact is wanting by means of which it is connected with the external world, and becomes part of a whole.
7
If we look on a white, strongly illumined surface, the eye is dazzled, and for a time is incapable of distinguishing objects moderately lighted.
8
The whole of the retina is acted on in each of these extreme states, and thus we can only experience one of these effects at a time. In the one case 6 we found the organ in the utmost relaxation and susceptibility; in the other 7 in an overstrained state, and scarcely susceptible at all.
9
If we pass suddenly from the one state to the other, even without supposing these to be the extremes, but only, perhaps, a change from bright to dusky, the difference is remarkable, and we find that the effects last for some time.
10
In passing from bright daylight to a dusky place we distinguish nothing at first: by degrees the eye recovers its susceptibility; strong eyes sooner than weak ones; the former in a minute, while the latter may require seven or eight minutes.
11

The fact that the eye is not susceptible to faint impressions of light, if we pass from light to comparative darkness, has led to curious mistakes in scientific observations. Thus an observer, whose eyes required some time to recover their tone, was long under the impression that rotten wood did not emit light at noon-day, even in a dark room. The fact was, he did not see the faint light, because he was in the habit of passing from bright sunshine to the dark room, and only subsequently remained so long there that the eye had time to recover itself.

The same may have happened to Doctor Wall, who, in the daytime, even in a dark room, could hardly perceive the electric light of amber.β

Our not seeing the stars by day, as well as the improved appearance of pictures seen through a double tube, is also to be attributed to the same cause.
12

If we pass from a totally dark place to one illumined by the sun, we are dazzled. In coming from a lesser degree of darkness to light that is not dazzling, we perceive all objects clearer and better: hence eyes that have been in a state of repose are in all cases better able to perceive moderately distinct appearances.

Prisoners who have been long confined in darkness acquire so great a susceptibility of the retina, that even in the dark (probably a darkness very slightly illumined) they can still distinguish objects.
13
In the act which we call seeing, the retina is at one and the same time in different and even opposite states. The greatest brightness, short of dazzling, acts near the greatest darkness. In this state we at once perceive all the intermediate gradations of chiaro-scuro, and all the varieties of hues.
14
We will proceed in due order to consider and examine these elements of the visible world, as well as the relation in which the organ itself stands to them, and for this purpose we take the simplest objects.
II. Effects of Black and White Objects on the Eye
15
In the same manner as the retina generally is affected by brightness and darkness, so it is affected by single bright or dark objects. If light and dark produce different results on the whole retina, so black and white objects seen at the same time produce the same states together which light and dark occasioned in succession.
16
A dark object appears smaller than a bright one of the same size. Let a white disk be placed on a black ground, and a black disk on a white ground, both being exactly similar in size; let them be seen together at some distance, and we shall pronounce the last to be about a fifth part smaller than the other. If the black circle be made larger by so much, they will appear equal.
Eastlake's Figure E.I.1
Eastlake's Figure E.I.1
17
Thus Tycho de Brahe remarked that the moon in conjunction (the darker state) appears about a fifth part smaller than when in opposition (the bright full state). The first crescent appears to belong to a larger disk than the remaining dark portion, which can sometimes be distinguished at the period of the new moon. Black dresses make people appear smaller than light ones. Lights seen behind an edge make an apparent notch in it. A ruler, behind which the flame of a light just appears, seems to us indented. The rising or setting sun appears to make a notch in the horizon.
18

Black, as the equivalent of darkness, leaves the organ in a state of repose; white, as the representative of light, excites it. We may, perhaps, conclude from the above experiment 16 that the unexcited retina, if left to itself, is drawn together, and occupies a less space than in its active state, produced by the excitement of light.

Hence Kepler says very beautifully:

Certum est vel in retinâ caussâ picturæ, vel in spiritibus caussâ impressionis, exsistere dilatationem lucidorum.
Paralip. in Vitellionem, p. 220. Scherfer expresses a similar conjecture.a
19
However this may be, both impressions derived from such objects remain in the organ itself, and last for some time, even when the external cause is removed. In ordinary experience we scarcely notice this, for objects are seldom presented to us which are very strongly relieved from each other, and we avoid looking at those appearances that dazzle the sight In glancing from one object to another; the succession of images appears to us distinct; we are not aware that some portion of the impression derived from the object first contemplated passes to that which is next looked at.
20
If in the morning, on waking, when the eye is very susceptible, we look intently at the bars of a window relieved against the dawning sky, and then shut our eyes or look towards a totally dark place, we shall see a dark cross on a light ground before us for some time.
21
Every image occupies a certain space on the retina, and of course a greater or less space in proportion as the object is seen near or at a distance. If we shut the eyes immediately after looking at the sun we shall be surprised to find how small the image it leaves appears.
22
If, on the other hand, we turn the open eye towards the side of a room, and consider the visionary image in relation to other objects, we shall always see it larger in proportion to the distance of the surface on which it is thrown. This is easily explained by the laws of perspective, according to which a small object near covers a great one at a distance.
23
The duration of these visionary impressions varies with the powers or structure of the eye in different individuals, just as the time necessary for the recovery of the tone of the retina varies in passing from brightness to darkness 10: it can be measured by minutes and seconds, indeed much more exactly than it could formerly have been by causing a lighted linstock to revolve rapidly, so as to appear a circle.b
24
But the force with which an impinging light impresses the eye is especially worthy of attention. The image of the sun lasts longest; other objects, of various degrees of brightness, leave the traces of their appearance on the eye for a proportionate time.
25
These images disappear by degrees, and diminish at once in distinctness and in size.
26
They are reduced from the contour inwards, and the impression on some persons has been that in square images the angles become gradually blunted till at last a diminished round image floats before the eye.
27
Such an image, when its impression is no more observable, can, immediately after, be again revived on the retina by opening and shutting the eye, thus alternately exciting and resting it.
28
Images may remain on the retina in morbid affections of the eye for fourteen, seventeen minutes, or even longer. This indicates extreme weakness of the organ, its inability to recover itself; while visions of persons or things which are the objects of love or aversion indicate the connexion between sense and thought.
29
If, while the image of the window-bars before mentioned lasts, we look upon a light grey surface, the cross will then appear light and the panes dark. In the first case 20 the image was like the original picture, so that the visionary impression also could continue unchanged; but in the present instance our attention is excited by a contrary effect being produced. Various examples have been given by observers of nature.
30

The scientific men who made observations in the Cordilleras saw a bright appearance round the shadows of their heads on some clouds. This example is a case in point; for, while they fixed their eyes on the dark shadow, and at the same time moved from the spot, the compensatory light image appeared to float round the real dark one. If we look at a black disk on a light grey surface, we shall presently, by changing the direction of the eyes in the slightest degree, see a bright halo floating round the dark circle.

A similar circumstance happened to myself: for while, as I sat in the open air, I was talking to a man who stood at a little distance from me relieved on a grey sky, it appeared to me, as I slightly altered the direction of my eyes, after having for some time looked fixedly at him, that his head was encircled with a dazzling light.

In the same way probably might be explained the circumstance that persons crossing dewy meadows at sunrise see a brightness round each other’s heads;4 the brightness in this case may be also iridescent, as the phenomena of refraction come into the account.

Thus again it has been asserted that the shadows of a balloon thrown on clouds were bordered with bright and somewhat variegated circles.

Beccaria made use of a paper kite in some experiments on electricity. Round this kite appeared a small shining cloud varying in size; the same brightness was even observed round part of the string. Sometimes it disappeared, and if the kite moved faster the light appeared to float to and fro for a few moments on the place before occupied. This appearance, which could not be explained by those who observed it at the time, was the image which the eye retained of the kite relieved as a dark mass on a bright sky; that image being changed into a light mass on a comparatively dark background.

In optical and especially in chromatic experiments, where the observer has to do with bright lights whether colourless or coloured, great care should be taken that the spectrum which the eye retains in consequence of a previous observation does not mix with the succeeding one, and thus affect the distinctness and purity of the impression.
31
These appearances have been explained as follows: That portion of the retina on which the dark cross 29 was impressed is to be considered in a state of repose and susceptibility. On this portion therefore the moderately light surface acted in a more lively manner than on the rest of the retina, which had just been impressed with the light through the panes, and which, having thus been excited by a much stronger brightness, could only view the grey surface as a dark.
32
This mode of explanation appears sufficient for the cases in question, but, in the consideration of phenomena hereafter to be adduced, we are forced to trace the effects to higher sources.
33
The eye after sleep exhibits its vital elasticity more especially by its tendency to alternate its impressions, which in the simplest form change from dark to light, and from light to dark. The eye cannot for a moment remain in a particular state determined by the object it looks upon. On the contrary, it is forced to a sort of opposition, which, in contrasting extreme with extreme, intermediate degree with intermediate degree, at the same time combines these opposite impressions, and thus ever tends to a whole, whether the impressions are successive, or simultaneous and confined to one image.
34
Perhaps the peculiarly grateful sensation which we experience in looking at the skilfully treated chiaroscuro of colourless pictures and similar works of art arises chiefly from the simultaneous impression of a whole, which by the organ itself is sought, rather than arrived at, in succession, and which, whatever may be the result, can never be arrested.
III. Grey Surfaces and Objects
35
A moderate light is essential to many chromatic experiments. This can be presently obtained by surfaces more or less grey, and thus we have at once to make ourselves acquainted with this simplest kind of middle tint, with regard to which it is hardly necessary to observe, that in many cases a white surface in shadow, or in a low light, may be considered equivalent to a grey.
36
Since a grey surface is intermediate between brightness and darkness, it admits of our illustrating a phenomenon before described 29 by an easy experiment.
37
Let a black object be held before a grey surface, and let the spectator, after looking steadfastly at it, keep his eyes unmoved while it is taken away: the space it occupied appears much lighter. Let a white object be held up in the same manner: on taking it away the space it occupied will appear much darker than the rest of the surface. Let the spectator in both cases turn his eyes this way and that on the surface, the visionary images will move in like manner.
38
A grey object on a black ground appears much brighter than the same object on a white ground. If both comparisons are seen together the spectator can hardly persuade himself that the two greys are identical. We believe this again to be a proof of the great excitability of the retina, and of the silent resistance which every vital principle is forced to exhibit when any definite or immutable state is presented to it. Thus inspiration already presupposes expiration; thus every systole its diastole. It is the universal formula of life which manifests itself in this as in all other cases. When darkness is presented to the eye it demands brightness, and vice versâ: it shows its vital energy, its fitness to receive the impression of the object, precisely by spontaneously tending to an opposite state.
IV. Dazzling Colourless Objects
39
If we look at a dazzling, altogether colourless object, it makes a strong lasting impression, and its after-vision is accompanied by an appearance of colour.
40

Let a room be made as dark as possible; let there be a circular opening in the window shutter about three inches in diameter, which may be closed or not at pleasure. The sun being suffered to shine through this on a white surface, let the spectator from some little distance fix his eyes on the bright circle thus admitted. The hole being then closed, let him look towards the darkest part of the room; a circular image will now be seen to float before him. The middle of this circle will appear bright, colourless, or somewhat yellow, but the border will at the same moment appear red.

After a time this red, increasing towards the centre, covers the whole circle, and at last the bright central point. No sooner, however, is the whole circle red than the edge begins to be blue, and the blue gradually encroaches inwards on the red. When the whole is blue the edge becomes dark and colourless. This darker edge again slowly encroaches on the blue till the whole circle appears colourless. The image then becomes gradually fainter, and at the same time diminishes in size. Here again we see how the retina recovers itself by a succession of vibrations after the powerful external impression it received. 25 26
41

By several repetitions similar in result, I found the comparative duration of these appearances in my own case to be as follows:—

I looked on the bright circle five seconds, and then, having closed the aperture, saw the coloured visionary circle floating before me. After thirteen seconds it was altogether red; twenty-nine seconds next elapsed till the whole was blue, and forty-eight seconds till it appeared colourless. By shutting and opening the eye I constantly revived the image 27, so that it did not quite disappear till seven minutes had elapsed.

Future observers may find these periods shorter or longer as their eyes may be stronger or weaker 23, but it would be very remarkable if, notwithstanding such variations, a corresponding proportion as to relative duration should be found to exist.
42

But this remarkable phenomenon no sooner excites our attention than we observe a new modification of it.

If we receive the impression of the bright circle as before, and then look on a light grey surface in a moderately lighted room, an image again floats before us; but in this instance a dark one: by degrees it is encircled by a green border that gradually spreads inwards over the whole circle, as the red did in the former instance. As soon as this has taken place a dingy yellow appears, and, filling the space as the blue did before, is finally lost in a negative shade.
43
These two experiments may be combined by placing a black and a white plane surface next each other in a moderately lighted room, and then looking alternately on one and the other as long as the impression of the light circle lasts: the spectator will then perceive at first a red and green image alternately, and afterwards the other changes. After a little practice the two opposite colours may be perceived at once, by causing the floating image to fall on the junction of the two planes. This can be more conveniently done if the planes are at some distance, for the spectrum then appears larger.
44
I happened to be in a forge towards evening at the moment when a glowing mass of iron was placed on the anvil; I had fixed my eyes steadfastly on it, and, turning round, I looked accidentally into an open coal-shed: a large red image now floated before my eyes, and, as I turned them from the dark opening to the light boards of which the shed was constructed, the image appeared half green, half red, according as it had a lighter or darker ground behind it. I did not at that time take notice of the subsequent changes of this appearance.
45
The after-vision occasioned by a total dazzling of the retina corresponds with that of a circumscribed bright object. The red colour seen by persons who are dazzled with snow belongs to this class of phenomena, as well as the singularly beautiful green colour which dark objects seem to wear after looking long on white paper in the sun. The details of such experiments may be investigated hereafter by those whose young eyes are capable of enduring such trials further for the sake of science.
46
With these examples we may also class the black letters which in the evening light appear red. Perhaps we might insert under the same category the story that drops of blood appeared on the table at which Henry IV of France had seated himself with the Duc de Guise to play at dice.ζ
V. Coloured Objects
47
We have hitherto seen the physiological colours displayed in the after-vision of colourless bright objects, and also in the after-vision of general colourless brightness; we shall now find analogous appearances if a given colour be presented to the eye: in considering this, all that has been hitherto detailed must be present to our recollection.
48
The impression of coloured objects remains in the eye like that of colourless ones, but in this case the energy of the retina, stimulated as it is to produce the opposite colour, will be more apparent.
49
Let a small piece of bright-coloured paper or silk stuff be held before a moderately lighted white surface; let the observer look steadfastly on the small coloured object, and let it be taken away after a time while his eyes remain unmoved; the spectrum of another colour will then be visible on the white plane. The coloured paper may be also left in its place while the eye is directed to another part of the white plane; the same spectrum will be visible there too, for it arises from an image which now belongs to the-eye.
50
In order at once to see what colour will be evoked by this contrast, the chromatic circle may be referred to. The colours are here arranged in a general way according to the natural order, and the arrangement will be found to be directly applicable in the present case; for the colours diametrically opposed to each other in this diagram are those which reciprocally evoke each other in the eye. Thus, yellow demands purple; orange, blue; red, green; and vice versâ: thus again all intermediate gradations reciprocally evoke each other; the simpler colour demanding the compound, and vice versâ.5
Eastlake's Chromatic Circle E.I.3
Eastlake's Chromatic Circle E.I.3
Goethe's Chromatic Circle G.I.1
Goethe's Chromatic Circle G.I.1
51
The cases here under consideration occur oftener than we are aware in ordinary life; indeed, an attentive observer sees these appearances everywhere, while, on the other hand, the uninstructed, like our predecessors, consider them as temporary visual defects, sometimes even as symptoms of disorders in the eye, thus exciting serious apprehensions. A few remarkable instances may here be inserted.
52
I had entered an inn towards evening, and, as a well-favoured girl, with a brilliantly fair complexion, black hair, and a scarlet bodice, came into the room, I looked attentively at her as she stood before me at some distance in half shadow. As she presently afterwards turned away, I saw on the white wall, which was now before me, a black face surrounded with a bright light, while the dress of the perfectly distinct figure appeared of a beautiful sea-green.
53
Among the materials for optical experiments, there are portraits with colours and shadows exactly opposite to the appearance of nature. The spectator, after having looked at one of these for a time, will see the visionary figure tolerably true to nature. This is conformable to the same principles, and consistent with experience, for, in the former instance, a negress with a white head-dress would have given me a white face surrounded with black. In the case of the painted figures, however, which are commonly small, the parts are not distinguishable by every one in the after-image.
54

A phenomenon which has before excited attention among the observers of nature is to be attributed, I am persuaded, to the same cause.

It has been stated that certain flowers, towards evening in summer, coruscate, become phosphorescent, or emit a momentary light. Some persons have described their observation of this minutely. I had often endeavoured to witness it myself, and had even resorted to artificial contrivances to produce it.

On the 19th of June, 1799, late in the evening, when the twilight was deepening into a clear night, as I was walking up and down the garden with a friend, we very distinctly observed a flame-like appearance near the oriental poppy, the flowers of which are remarkable for their powerful red colour. We approached the place and looked attentively at the flowers, but could perceive nothing further, till at last, by passing and repassing repeatedly, while we looked sideways on them, we succeeded in renewing the appearance as often as we pleased. It proved to be a physiological phenomenon, such as others we have described, and the apparent coruscation was nothing but the spectrum of the flower in the compensatory blue-green colour.

In looking directly at a flower the image is not produced, but it appears immediately as the direction of the eye is altered. Again, by looking sideways on the object, a double image is seen for a moment, for the spectrum then appears near and on the real object.

The twilight accounts for the eye being in a perfect state of repose, and thus very susceptible, and the colour of the poppy is sufficiently powerful in the summer twilight of the longest days to act with full effect and produce a compensatory image. I have no doubt these appearances might be reduced to experiment, and the same effect produced by pieces of coloured paper. Those who wish to take the most effectual means for observing the appearance in nature—suppose in a garden—should fix the eyes on the bright flowers selected for the purpose, and, immediately after, look on the gravel path. This will be seen studded with spots of the opposite colour. The experiment is practicable on a cloudy day, and even in the brightest sunshine, for the sun-light, by enhancing the brilliancy of the flower, renders it fit to produce the compensatory colour sufficiently distinct to be perceptible even in a bright light. Thus, peonies produce beautiful green, marigolds vivid blue spectra.
55
As the opposite colour is produced by a constant law in experiments with coloured objects on portions of the retina, so the same effect takes place when the whole retina is impressed with a single colour. We may convince ourselves of this by means of coloured glasses. If we look long through a blue pane of glass, everything will afterwards appear in sunshine to the naked eye, even if the sky is grey and the scene colourless. In like manner, in taking off green spectacles, we see all objects in a red light. Every decided colour does a certain violence to the eye, and forces the organ to opposition.
56
We have hitherto seen the opposite colours producing each other successively on the retina: it now remains to show by experiment that the same effects can exist simultaneously. If a coloured object impinges on one part of the retina, the remaining portion at the same moment has a tendency to produce the compensatory colour. To pursue a former experiment, if we look on a yellow piece of paper placed on a white surface, the remaining part of the organ has already a tendency to produce a purple hue on the colourless surface: in this case the small portion of yellow is not powerful enough to produce this appearance distinctly, but, if a white paper is placed on a yellow wall, we shall see the white tinged with a purple hue.
57
Although this experiment may be made with any colours, yet red and green are particularly recommended for it, because these colours seem powerfully to evoke each other. Numerous instances occur in daily experience. If a green paper is seen through striped or flowered muslin, the stripes or flowers will appear reddish. A grey building seen through green palisades appears in like manner reddish. A modification of this tint in the agitated sea is also a compensatory colour: the light side of the waves appears green in its own colour, and the shadowed side is tinged with the opposite hue. The different direction of the waves with reference to the eye produces the same effect. Objects seen through an opening in a red or green curtain appear to wear the opposite hue. These appearances will present themselves to the attentive observer on all occasions, even to an unpleasant degree.
58
Having made ourselves acquainted with the simultaneous exhibition of these effects in direct cases, we shall find that we can also observe them by indirect means. If we place a piece of paper of a bright orange colour on the white surface, we shall, after looking intently at it, scarcely perceive the compensatory colour on the rest of the surface: but when we take the orange paper away, and when the blue spectrum appears in its place, immediately as this spectrum becomes fully apparent, the rest of the surface will be overspread, as if by a flash, with a reddish-yellow light, thus exhibiting to the spectator in a lively manner the productive energy of the organ, in constant conformity with the same law.
59
As the compensatory colours easily appear, where they do not exist in nature, near and after the original opposite ones, so they are rendered more intense where they happen to mix with a similar real hue. In a court which was paved with grey limestone flags, between which grass had grown, the grass appeared of an extremely beautiful green when the evening clouds threw a scarcely perceptible reddish light on the pavement. In an opposite case we find, in walking through meadows, where we see scarcely anything but green, the stems of trees and the roads often gleam with a reddish hue. This tone is not uncommon in the works of landscape painters, especially those who practice in water-colours: they probably see it in nature, and thus, unconsciously imitating it, their colouring is criticized as unnatural.
60
These phenomena are of the greatest importance, since they direct our attention to the laws of vision, and are a necessary preparation for future observations on colours. They show that the eye especially demands completeness, and seeks to eke out the colorific circle in itself. The purple or violet colour suggested by yellow contains red and blue; orange, which responds to blue, is composed of yellow and red; green, uniting blue and yellow, demands red; and so through all gradations of the most complicated combinations. That we are compelled in this case to assume three leading colours has been already remarked by other observers.
61
When in this completeness the elements of which it is composed are still appreciable by the eye, the result is justly called harmony. We shall subsequently endeavour to show how the theory of the harmony of colours may be deduced from these phenomena, and how, simply through these qualities, colours may be capable of being applied to aesthetic purposes. This will be shown when we have gone through the whole circle of our observations, returning to the point from which we started.
VI. Coloured Shadows
62
Before, however, we proceed further, we have yet to observe some very remarkable cases of the vivacity with which the suggested colours appear in the neighbourhood of others: we allude to coloured shadows. To arrive at these we first turn our attention to shadows that are colourless or negative.
63
A shadow cast by the sun, in its full brightness, on a white surface, gives us no impression of colour; it appears black, or, if a contrary light (here assumed to differ only in degree) can act upon it, it is only weaker, half-lighted, grey.
64
Two conditions are necessary for the existence of coloured shadows: first, that the principal light tinge the white surface with some hue; secondly, that a contrary light illumine to a certain extent the cast shadow.
65
Let a short, lighted candle be placed at twilight on a sheet of white paper. Between it and the declining daylight let a pencil be placed upright, so that its shadow thrown by the candle may be lighted, but not overcome, by the weak daylight: the shadow will appear of the most beautiful blue.
66
That this shadow is blue is immediately evident; but we can only persuade ourselves by some attention that the white paper acts as a reddish yellow, by means of which the complemental blue is excited in the eye.10
67
In all coloured shadows, therefore, we must presuppose a colour excited or suggested by the hue of the surface on which the shadow is thrown. This may be easily found to be the case by attentive consideration, but we may convince ourselves at once by the following experiment.
68
Place two candles at night opposite each other on a white surface; hold a thin rod between them upright, so that two shadows be cast by it; take a coloured glass and hold it before one of the lights, so that the white paper appear coloured; at the same moment the shadow cast by the coloured light and slightly illumined by the colourless one will exhibit the complemental hue.
69
An important consideration suggests itself here, to which we shall frequently have occasion to return. Colour itself is a degree of darkness IV ; hence Kircher is perfectly right in calling it lumen opacatum. As it is allied to shadow, so it combines readily with it; it appears to us readily in and by means of shadow the moment a suggesting cause presents itself. We could not refrain from adverting at once to a fact which we propose to trace and develop hereafter.14
70
Select the moment in twilight when the light of the sky is still powerful enough to cast a shadow which cannot be entirely effaced by the light of a candle. The candle may be so placed that a double shadow shall be visible, one from the candle towards the daylight, and another from the daylight towards the candle. If the former is blue the latter will appear orange-yellow: this orange-yellow is in fact, however, only the yellow-red light of the candle diffused over the whole paper, and which becomes visible in shadow.
71
This is best exemplified by the former experiment with two candles and coloured glasses. The surprising readiness with which shadow assumes a colour will again invite our attention in the further consideration of reflections and elsewhere.
72
Thus the phenomena of coloured shadows may he traced to their cause without difficulty. Henceforth let any one who sees an instance of the kind observe only with what hue the light surface on which they are thrown is tinged. Nay, the colour of the shadow may be considered as a chromatoscope of the illumined surface, for the spectator may always assume the colour of the light to be the opposite of that of the shadow, and by an attentive examination may ascertain this to be the fact in every instance.
73
These appearances have been a source of great perplexity to former observers: for, as they were remarked chiefly in the open air, where they commonly appeared blue, they were attributed to a certain inherent blue or blue colouring quality in the air. The inquirer can, however, convince himself, by the experiment with the candle in a room, that no kind of blue light or reflection is necessary to produce the effect in question. The experiment may be made on a cloudy day with white curtains drawn before the light, and in a room where no trace of blue exists, and the blue shadow will be only so much the more beautiful.
74

De Saussure, in the description of his ascent of Mont Blanc, says:

A second remark, which may not be uninteresting, relates to the colour of the shadows. These, notwithstanding the most attentive observation, we never found dark blue, although this had been frequently the case in the plain. On the contrary, in fifty-nine instances we saw them once yellowish, six times pale bluish, eighteen times colourless or black, and thirty-four times pale violet. Some natural philosophers suppose that these colours arise from accidental vapours diffused in the air, which communicate their own hues to the shadows; not that the colours of the shadows are occasioned by the reflection of any given sky colour or interposition of any given air colour: the above observations seem to favour this opinion.

The instances given by De Saussure may be now explained and classed with analogous examples without difficulty.

At a great elevation the sky was generally free from vapours, the sun shone in full force on the snow, so that it appeared perfectly white to the eye: in this case they saw the shadows quite colourless. If the air was charged with a certain degree of vapour, in consequence of which the light snow would assume a yellowish tone, the shadows were violet-coloured, and this effect, it appears, occurred oftenest. They saw also bluish shadows, but this happened less frequently; and that the blue and violet were pale was owing to the surrounding brightness, by which the strength of the shadows was mitigated. Once only they saw the shadow yellowish: in this case, as we have already seen 70, the shadow is cast by a colourless light, and slightly illumined by a coloured one.
75

In travelling over the Harz in winter, I happened to descend from the Brocken towards evening; the wide slopes extending above and below me, the heath, every insulated tree and projecting rock, and all masses of both, were covered with snow or hoar-frost. The sun was sinking towards the Oder ponds37 . During the day, owing to the yellowish hue of the snow, shadows tending to violet had already been observable; these might now be pronounced to be decidedly blue, as the illumined parts exhibited a yellow deepening to orange.

But as the sun at last was about to set, and its rays, greatly mitigated by the thicker vapours, began to diffuse a most beautiful red colour over the whole scene around me, the shadow colour changed to a green, in lightness to be compared to a sea-green, in beauty to the green of the emerald. The appearance became more and more vivid: one might have imagined oneself in a fairy world, for every object had clothed itself in the two vivid and so beautifully harmonising colours, till at last, as the sun went down, the magnificent spectacle was lost in a grey twilight, and by degrees in a clear moon-and-starlight night.
76
One of the most beautiful instances of coloured shadows may be observed during the full moon. The candle-light and moon-light may be contrived to be exactly equal in force; both shadows may be exhibited with equal strength and clearness, so that both colours balance each other perfectly. A white surface being placed opposite the full moon, and the candle being placed a little on one side at a due distance, an opaque body is held before the white plane. A double shadow will then be seen: that cast by the moon and illumined by the candle-light will be a powerful red-yellow; and contrariwise, that cast by the candle and illumined by the moon will appear of the most beautiful blue. The shadow, composed of the union of the two shadows, where they cross each other, is black. The yellow shadow 74 cannot perhaps be exhibited in a more striking manner. The immediate vicinity of the blue and the interposing black shadow make the appearance the more agreeable. It will even be found, if the eye dwells long on these colours, that they mutually evoke and enhance each other, the increasing red in the one still producing its contrast, namley a kind of sea-green.
77
We are here led to remark that in this, and in all cases, a moment or two may perhaps be necessary to produce the complemental colour. The retina must be first thoroughly impressed with the demanding hue before the responding one can be distinctly observable.
78
When divers are under water, and the sunlight shines into the diving-bell, everything is seen in a red light (the cause of which will be explained hereafter), while the shadows appear green. The very same phenomenon which I observed on a high mountain 75 is presented to others in the depths of the sea, and thus Nature throughout is in harmony with herself.
79
Some observations and experiments which equally illustrate what has been stated with regard to coloured objects and coloured shadows may be here added. Let a white paper blind be fastened inside the window on a winter evening; in this blind let there be an opening, through which the snow of some neighbouring roof can be seen. Towards dusk let a candle be brought into the room; the snow seen through the opening will then appear perfectly blue, because the paper is tinged with warm yellow by the candle-light. The snow seen through the aperture is here equivalent to a shadow illumined by a contrary light 76, and may also represent a grey disk on a coloured surface 56.
80

Another very interesting experiment may conclude these examples. If we take a piece of green glass of some thickness, and hold it so that the window bars be reflected in it, they will appear double owing to the thickness of the glass. The image which is reflected from the under surface of the glass will be green; the image which is reflected from the upper surface, and which should be colourless, will appear red.

The experiment may be very satisfactorily made by pouring water into a vessel, the inner surface of which can act as a mirror; for both reflections may first be seen colourless while the water is pure, and then by tinging it, they will exhibit two opposite hues.
VII. Faint Lights
81
Light, in its full force, appears purely white, and it gives this impression also in its highest degree of dazzling splendour. Light, which is not so powerful, can also, under various conditions, remain colourless. Several naturalists and mathematicians have endeavoured to measure its degrees—Lambert, Bouguer, Rumfortθ .
82
Yet an appearance of colour presently manifests itself in fainter lights, for in their relation to absolute light they resemble the coloured spectra of dazzling objects 39.
83
A light of any kind becomes weaker, either when its own force, from whatever cause, is diminished, or when the eye is so circumstanced or placed, that it cannot be sufficiently impressed by the action of the light. Those appearances which may be called objective, come under the head of physical colours. We will only advert here to the transition from white to red heat in glowing iron. We may also observe that the flames of lights at night appear redder in proportion to their distance from the eye.38
84
Candle-light at night acts as yellow when seen near; we can perceive this by the effect it produces on other colours. At night a pale yellow is hardly to be distinguished from white; blue approaches to green, and rose-colour to orange.
85
Candle-light at twilight acts powerfully as a yellow light: this is best proved by the purple blue shadows which, under these circumstances, are evoked by the eye.
86
The retina may be so exited by a strong light that it cannot perceive fainter lights 11: if it perceive these they appear coloured: hence candle-light by day appears reddish, thus resembling, in its relation to fuller light, the spectrum of a dazzling object; nay, if at night we look long and intently on the flame of a light, it appears to increase in redness.
87
There are faint lights which, notwithstanding their moderate lustre, give an impression of a white, or, at the most, of a light yellow appearance on the retina; such as the moon in its full splendour. Rotten wood has even a kind of bluish light. All this will hereafter be the subject of further remarks.
88
If at night we place a light near a white or greyish wall so that the surface be illumined from this central point to some extent, we find, on observing the spreading light at some distance, that the boundary of the illumined surface appears to be surrounded with a yellow circle, which on the outside tends to red-yellow. We thus observe that when light direct or reflected does not act in its full force, it gives an impression of yellow, of reddish, and lastly even of red. Here we find the transition to halos which we are accustomed to see in some mode or other round luminous points.
VIII. Subjective Halos
89
Halos may be divided into subjective and objective. The latter will be considered under the physical colours; the first only belong here. These are distinguished from the objective halos by the circumstance of their vanishing when the point of light which produces them on the retina is covered.
90
We have before noticed the impression of a luminous object on the retina, and seen that it appears larger: but the effect is not at an end here, it is not confined to the impression of the image; an expansive action also takes place, spreading from the centre.
91
That a nimbus of this kind is produced round the luminous image in the eye may be best seen in a dark room, if we look towards a moderately large opening in the window-shutter. In this case the bright image is surrounded by a circular misty light. I saw such a halo bounded by a yellow and yellow-red circle on opening my eyes at dawn, on an occasion when I passed several nights in a bed-carriage.
92
Halos appear most vivid when the eye is susceptible from having been in a state of repose. A dark background also heightens their appearance. Both causes account for our seeing them so strong if a light is presented to the eyes on waking at night. These conditions were combined when Descartes after sleeping, as he sat in a ship, remarked such a vividly-coloured halo round the light.
93
A light must shine moderately, not dazzle, in order to produce the impression of a halo in the eye; at all events the halos of dazzling lights cannot be observed. We see a splendour of this kind round the image of the sun reflected from the surface of water.
94
A halo of this description, attentively observed, is found to be encircled towards its edge with a yellow border: but even here the expansive action, before alluded to, is not at an end, but appears still to extend in varied circles.
95
Several cases seem to indicate a circular action of the retina, whether owing to the round form of the eye itself and its different parts, or to some other cause.
96
If the eye is pressed only in a slight degree from the inner corner, darker or lighter circles appear. At night, even without pressure, we can sometimes perceive a succession of such circles emerging from, or spreading over, each other.
97
We have already seen that a yellow border is apparent round the white space illumined by a light placed near it. This may be a kind of objective halo. 88
98
Subjective halos may be considered as the result of a conflict between the light and a living surface. From the conflict between the exciting principle and the excited, an undulating motion arises, which may be illustrated by a comparison with the circles on water. The stone thrown in drives the water in all directions; the effect attains a maximum, it reacts, and being opposed, continues under the surface. The effect goes on, culminates again, and thus the circles are repeated. If we have ever remarked the concentric rings which appear in a glass of water on trying to produce a tone by rubbing the edge; if we call to mind the intermitting pulsations in the reverberations of bells, we shall approach a conception of what may take place on the retina when the image of a luminous object impinges on it, not to mention that as a living and elastic structure, it has al ready a circular principle in its organization.39
99
The bright circular space which appears round the shining object is yellow, ending in red: then follows a greenish circle, which is terminated by a red border. This appears to be the usual phenomenon where the luminous body is somewhat considerable in size. These halos become greater the more distant we are from the luminous object.
100
Halos may, however, appear extremely small and numerous when the impinging image is minute, yet powerful, in its effect. The experiment is best made with a piece of gold-leaf placed on the ground and illumined by the sun. In these cases the halos appear in variegated rays. The iridescent appearance produced in the eye when the sun pierces through the leaves of trees seems also to belong to the same class of phenomena.
Appendix: Pathological Colours
101
We are now sufficiently acquainted with the physiological colours to distinguish them from the pathological. We know what appearances belong to the eye in a healthy state, and are necessary to enable the organ to exert its complete vitality and activity.
102
Morbid phenomena indicate in like manner the existence of organic and physical laws: for if a living being deviates from those rules with reference to which it is constructed, it still seeks to agree with the general vitality of nature in conformity with general laws, and throughout its whole course still proves the constancy of those principles on which the universe has existed, and by which it is held together.
103
We will here first advert to a very remarkable state in which the vision of many persons is found to be. As it presents a deviation from the ordinary mode of seeing colours, it might be fairly classed under morbid impressions; but as it is consistent in itself, as it often occurs, may extend to several members of a family, and probably does not admit of cure, we may consider it as bordering only on the nosological cases, and therefore place it first.
104
I was acquainted with two individuals not more than twenty years of age, who were thus affected: both had bluish-grey eyes, an acute sight for near and distant objects, by day-light and candle-light, and their mode of seeing colours was in the main quite similar.
105
They agreed with the rest of the world in denominating white, black, and grey in the usual manner. Both saw white untinged with any hue. One saw a somewhat brownish appearance in black, and in grey a somewhat reddish tinge. In general they appeared to have a very delicate perception of the gradations of light and dark.
106
They appeared to see yellow, red-yellow, and yellow-red40 , like others: in the last case they said they saw the yellow passing as it were over the red as if glazed: some thickly-ground carmine, which had dried in a saucer, they called red.
107
But now a striking difference presented itself. If the carmine was passed thinly over the white saucer, they would compare the light colour thus produced to the colour of the sky, and call it blue. If a rose was. shown them beside it, they would, in like manner, call it blue; and in all the trials which were made, it appeared that they could not distinguish light blue from rose-colour. They confounded rose-colour, blue, and violet on all occasions: these colours only appeared to them to be distinguished from each other by delicate shades of lighter, darker, intenser, or fainter appearance.
108
Again they could not distinguish green from dark orange, nor, more especially, from a red brown.
109
If any one, accidentally conversing with these individuals, happened to question them about surrounding objects, their answers occasioned the greatest perplexity, and the interrogator began to fancy his own wits were out of order. With some method we may, however, approach to a nearer knowledge of the law of this deviation from the general law.
110
These persons, as may be gathered from what has been stated, saw fewer colours than other people: hence arose the confusion of different colours. They called the sky rose-colour, and the rose blue, or vice versâ. The question now is: did they see both blue or both rose-colour? did they see green orange, or orange green?
111
This singular enigma appears to solve itself, if we assume that they saw no blue, but, instead of it, a light pure red, a rose-colour. We can comprehend what would be the result of this by means of the chromatic diagram.
112
If we take away blue from the chromatic circle we shall miss violet and green as well. Pure red occupies the place of blue and violet, and in again mixing with yellow the red produces orange where green should be.
113
Professing to be satisfied with this mode of explanation, we have named this remarkable deviation from ordinary vision "AcyanoblepsiaVI ." We have prepared some coloured figures for its further elucidation, and in explaining these we shall add some further details. Among the examples will be found a landscape, coloured in the mode in which the individuals alluded to appeared to see nature: the sky rose-colour, and all that should be green varying from yellow to brown red, nearly as foliage appears to us in autumn.41 c
Goethe's Acyanoblepsia Landscape G.I.11
Goethe's Acyanoblepsia Landscape G.I.11
114
We now proceed to speak of morbid and other extraordinary affections of the retina, by which the eye may be susceptible of an appearance of light without external light, reserving for a future occasion the consideration of galvanic light.
115
If the eye receives a blow, sparks seem to spread from it. In some states of body, again, when the blood is heated, and the system much excited, if the eye is pressed first gently, and then more and more strongly, a dazzling and intolerable light may be excited.
116
If those who have been recently couched experience pain and heat in the eye, they frequently see fiery flashes and sparks: these symptoms last sometimes for a week or fortnight, or till the pain and heat diminish.
117
A person suffering from ear-ache saw sparks and balls of light in the eye during each attack, as long as the pain lasted.
118
Persons suffering from worms often experience extraordinary appearances in the eye, sometimes sparks of fire, sometimes spectres of light, sometimes frightful figures, which they cannot by an effort of the will cease to see: sometimes these appearances are double.
119
Hypochondriacs frequently see dark objects, such as threads, hairs, spiders, flies, wasps. These appearances also exhibit themselves in the incipient hard cataract. Many see semitransparent small tubes, forms like wings of insects, bubbles of water of various sizes, which fall slowly down, if the eye is raised: sometimes these congregate together so as to resemble the spawn of frogs; sometimes they appear as complete spheres, sometimes in the form of lenses.
120
As light appeared, in the former instances, without external light, so also these images appear without corresponding external objects. The images are sometimes transient, sometimes they last during the patient’s life. Colour, again, frequently accompanies these impressions: for hypochondriacs often see yellow-red stripes in the eye: these are generally more vivid find numerous in the morning, or when fasting.
121
We have before seen that the impression of any object may remain for a time in the eye: this we have found to be a physiological phenomenon 23: the excessive duration of such an impression, on the other hand, may be considered as morbid.
122
The weaker the organ the longer the impression of the image lasts. The retina does not so soon recover itself; and the effect may be considered as a kind of paralysis 28.
123
This is not to be wondered at in the case of dazzling lights. If any one looks at the sun, he may retain the image in his eyes for several days. Boyle relates an instance of ten years.
124
The same takes place, in a certain degree, with regard to objects that are not dazzling. Büschι relates of himself that the image of an engraving, complete in all its parts, was impressed on his eye for seventeen minutes.
125
A person inclined to fulness of blood retained the image of a bright red calico, with white spots, many minutes in the eye, and saw it float before everything like a veil. It only disappeared by rubbing the eye for some time.
126
Scherferκ observes that the red colour, which is the consequence of a powerful impression of light, may last for some hours.
127
As we can produce an appearance of light on the retina by pressure on the eyeball, so by a gentle pressure a red colour appears, thus corresponding with the after-image of an impression of light.
128
Many sick persons, on awaking, see everything in the colour of the morning sky, as if through a red veil: so, if in the evening they doze and wake again, the same appearance presents itself. It remains for some minutes, and always disappears if the eye is rubbed a little. Red stars and balls sometimes accompany the impression. This state may last for a considerable time.
129
The aëronauts, particularly Zambeccari and his companions, relate that they saw the moon blood-red at the highest elevation. As they had ascended above the vapours of the earth, through which we see the moon and sun naturally of such a colour, it may be suspected that this appearance may be classed with the pathological colours. The senses, namely, may be so influenced by an unusual state, that the whole nervous system, and particularly the retina, may sink into a kind of inertness and inexcitability. Hence it is not impossible that the moon might act as a very subdued light, and thus produce the impression of the red colour. The sun even appeared blood-red to the aeronauts of Hamburgh. If those who are at some elevation in a balloon scarcely hear each other speak, may not this, too, be attributed to the inexcitable state of the nerves as well as to the thinness of the air?
130
Objects are often seen by sick persons in variegated colours. Boyle relates an instance of a lady, who, after a fall by which an eye was bruised, saw all objects, but especially white objects, glittering in colours, even to an intolerable degree.
131
Physicians give the name of "Chrupsia" to an affection of the sight, occurring in typhoid maladies. In these cases the patients state that they see the boundaries of objects coloured where light and dark meet. A change probably takes place in the humours of the eye, through which their achromatism is affected.
132
In cases of milky cataract, a very turbid crystalline lens causes the patient to see a red light. In a case of this kind, which was treated by the application of electricity, the red light changed by degrees to yellow, and at last to white, when the patient again began to distinguish objects. These changes of themselves warranted the conclusion that the turbid state of the lens was gradually approaching the transparent state. We shall be enabled easily to trace this effect to its source as soon as we become better acquainted with the physical colours.
133
If again it may be assumed that a jaundiced patient sees through an actually yellow-coloured humour, we are at once referred to the department of chemical colours, and it is thus evident that we can only thoroughly investigate the chapter of pathological colours when we have made ourselves acquainted with the whole range of the remaining phenomena. What has been adduced may therefore suffice for the present, till we resume the further consideration of this portion of our subject.
134

In conclusion we may, however, at once advert to some peculiar states or dispositions of the organ.

There are painters who, instead of rendering the colours of nature, diffuse a general tone, a warm or cold hue, over the picture. In some, again, a predilection for certain colours displays itself; in others a want of feeling for harmony.
135
Lastly, it is also worthy of remark, that savage nations, uneducated people, and children have a great predilection for vivid colours; that animals are excited to rage by certain colours; that people of refinement avoid vivid colours in their dress and the objects that are about them, and seem inclined to banish them altogether from their presence.42
Goethe's Footnotes
I Vasari observes, "L’unione nella pittura è una discordance di colon diversi accordati insidme."—Vol. i. c. 18. This observation is repeated by various writers on art in nearly the same words, and at last appears in Sandrart: "Concordia, potissimum picture decus, in discordiâ consistit, et quasi litigio colorum."—P. i. c. 5. The source, perhaps, is Aristotle: he observes, "We are delighted with harmony, because it is the union of contrary principles having a ratio to each other."—Problem.
II See "Occolti Trattato de’ Colori.” Parma, 1568.
III "Volendo l’uomo accoppiare insième colori che all’occhio dilettino— porrà insième il berrettino col leonato; il verde-giallo con l’incarnato e rosso; il turchino con i’arangi; il morello col verde oscuro; il nero col bianco; il bianco con l’incarnato."—Dialogo di M. Lodovico Dolce nel quale si ragiona della qualita, diversità, e proprietà de’ colori. Venezia, 1565.
IV (σκιερόν η )
V In the Dresden Gallery, a picture attributed to Titian—at all events a lucid Venetian picture—hangs next the St. George of Correggio. After looking at tie latter, the Venetian work appears glassy and unsubstantial, but on reversing the order of comparison, the Correggio may be said to suffer more, and for a moment its fine transitions of light and shade seem changed to heaviness.
VI Non-perception of blue.
Eastlake's Footnotes
1 The German distinction between subject and object is so generally understood and adopted, that it is hardly necessary to explain that the subject is the individual, in this case the beholder; the object, all that is without him.
2 Trattato della Pittura, Romas, 1817, p. 143-223. This edition, published from a Vatican MS., contains many observations not included in the former editions.
3 A few notes (marked with inverted commasγ and with the signature S.F.) have been kindly furnished by a scientific friend.
4 See The Life of Benvenuto Cellini, vol. i. p. 453. Milan edition, 1806δ
5

Every treatise on the harmonious combination of colours contains the diagram of the chromatic circle more or less elaborately constructed. These diagrams, if intended to exhibit the contrasts produced by the action and re-action of the retina, have one common defect. The opposite colours are made equal in intensity; whereas the complements! colour pictured on the retina is always less vivid, and always darker or lighter than the original colour. This variety undoubtedly accords more with harmonious effects in painting.

The opposition of two pure hues of equal intensity, differing only in the abstract quality of colour, would immediately be pronounced crude and inharmonious. It would not, however, be strictly correct to say that such a contrast is too violent; on the contrary, it appears the contrast is not carried far enough, for though differing in colour, the two hues may be exactly similar in purity and intensity. Complete contrast, on the other hand, supposes dissimilarity in all respects.

In addition to the mere difference of hue, the eye, it seems, requires difference in the lightness or darkness of the hue. The spectrum of a colour relieved as a dark on a light ground, is a light colour on a dark ground, and vice versâ. Thus, if we look at a bright red wafer on the whitest surface, the complemental image will be still lighter than the white surface; if the same wafer is placed on a black surface, the complemental image will be still darker. The colour of both these spectra may be called greenish, but it is evident that a colour must be scarcely appreciable as such, if it is lighter than white and darker than black. It is, however, to be remarked, that the white surface round the light greenish image seems tinged with a reddish hue, and the black surface round the dark image becomes slightly illuminated with the same colour, thus in both cases assisting to render the image apparent 58.

The difficulty or impossibility of describing degrees of colour in words, has also had a tendency to mislead, by conveying the idea of more positive hues than the physiological contrast warrants. Thus, supposing scarlet to be relieved as a dark, the complemental colour is so light in degree and so faint in colour, that it should be called a pearly grey; whereas the theorists, looking at the quality of colour abstractedly, would call it a green-blue, and the diagram would falsely present such a hue equal in intensity to scarlet, or as nearly equal as possible.

Even the difference of mass which good taste requires may be suggested by the physiological phenomena, for unless the complemental image is suffered to fall on a surface precisely as near to the eye as that on which the original colour was displayed, it appears larger or smaller than the original object 22, and this in a rapidly increasing proportion. Lastly, the shape itself soon becomes changed 26.

That vivid colour demands the comparative absence of colour, either on a lighter or darker scale, as its contrast, may be inferred again from the fact that bright colourless objects produce strongly coloured spectra. In darkness, the spectrum which is first white, or nearly white, is followed by red: in light, the spectrum which is first black, is followed by green 39 40 41 42 43 44. All colour, as the author observes 259, is to be considered as half-light, inasmuch as it is in every case lighter than black and darker than white. Hence no contrast of colour with colour, or even of colour with black or white, can be so great (as regards lightness or darkness) as the contrast of black and white, or light and dark abstractedly. This distinction between the differences of degree and the differences of kind is important, since a just application of contrast in colour may be counteracted by an undue difference in lightness or darkness. The mere contrast of colour is happily employed in some of Guido's lighter pictures, but if intense darks had been opposed to his delicate carnations, their comparative whiteness would have been unpleasantly apparent. On the other hand, the flesh colour in Giorgione, Sebastian del Piombo (his best imitator), and Titian, was sometimes so extremely glowing6 that the deepest colours, and black, were indispensable accompaniments. The manner of Titian as distinguished from his imitation of Giorgione, is golden rather than fiery, and his biographers are quite correct in saying that he was fond of opposing red (lake) and blue to his flesh,7 The correspondence of these contrasts with the physiological phenomena will be immediately apparent, while the occasional practice of Rubens in opposing bright red to a still cooler flesh-colour, will be seen to be equally consistent.

The effect of white drapery (the comparative absence of colour) in enhancing the glow of Titian's flesh-colour, has been frequently pointed out:8 the shadows of white thus opposed to flesh, often present, again, the physiological contrast, however delicately, according to the hue of the carnation. The lights, on the other hand, are not, and probably never were, quite white, but from the first, partook of the quality of depth, a quality assumed by the colourists to pervade every part of a picture more or less.9

It was before observed that the description of colours in words may often convey ideas of too positive a nature, and it may be remarked generally that the colours employed by the great masters are, in their ultimate effect, more or less subdued or broken. The physiological contrasts are, however, still applicable in the most comparatively neutral scale. Again, the works of the colourists show that these oppositions are not confined to large masses (except perhaps in works to be seen only at a great distance); on the contrary, they are more or less apparent in every part, and when at last the direct and intentional operations of the artist may have been insufficient to produce them in their minuter degrees, the accidental results of glazing and other methods may be said to extend the contrasts to infinity. In such productions where every smallest portion is an epitome of the whole, the eye still appreciates the fascinating effect of contrast, and the work is pronounced to be true and complete, in the best sense of the words.

The Venetian method of scumbling and glazing exhibits these minuter contrasts within each other, and is thus generally considered more refined than the system of breaking the colours, since it ensures a fuller gradation of hues, and produces another class of contrasts, those, namely, which result from degrees of transparence and opacity. In some of the Flemish and Dutch masters, and sometimes in Reynolds, the two methods are combined in great perfection.

The chromatic diagram does not appear to be older than the last century. It is one of those happy adaptations of exacter principles to the objects of taste which might have been expected from Leonardo da Vinci. That its true principle was duly felt is abundantly evident from the works of the colourists, as well as from the general observations of early writers.I The more practical directions occasionally to be met with in the treatises of Leon Battista Alberti, Leonardo da Vinci and others, are conformable to the same system. Some Italian works, not written by painters, which pretend to describe this harmony, are, however, very imperfect.II A passage in Lodovico Dolce’s Dialogue on Colours is perhaps the only one worth quoting. "He," says that writer,

who wishes to combine colours that are agreeable to the eye, will put grey next dusky orange; yellow-green next rose-colour; blue next orange; dark purple, black, next dark-green; white next black, and white next flesh-colour.
III early

The Dialogue on Painting, by the same author, has the reputation of containing some of Titian’s precepts: if the above passage may be traced to the same source, it must be confessed that it is almost the only one of the kind in the treatise from which it is taken.

6 "Ardito veramente alquanto, sanguigno, e quasi flammeggiante." —Zanetti della Pittura Venexiana,Ven. 1771, p. 90. Warm as the flesh colour of the colourists is, it still never approaches a positive hue, if we except some examples in frescoes and other works intended to be seen at a great distance. Zanrtti, speaking of a fresco by Giorgione, now almost obliterated, compares the colour to "un vivo raggio di cocente sole.”—Forte Pittvre a fresco dei Principali Maestri Veneztani.Ven. 1760.
7 Ridolfi.
8 Zanetti, I. ii.
9

Two great authorities, divided by more than three centuries, Leon Battista Alberti and Reynolds, have recommended this subdued treatment of white. "It is to be remembered," says the first,

that no surface should be made so white that it cannot be made more so. In white dresses again, it is necessary to stop far short of the last degree of whiteness. —Delta Pittwa, 1. ii., compare with Reynolds, vol. i. die. 8.
10

In some of these cases there can be no doubt that Goethe attributes the contrast too exclusively to the physiological cause, without making sufficient allowance for the actual difference in the colour of the lights. The purely physical nature of some coloured shadows was pointed out by Pohlmann; and Dr. Eckermann took some pains to convince Goethe of the necessity of making such a distinction. Goethe at first adhered to his extreme view, but some time afterwards confessed to Dr. Eckermann, that in the case of the blue shadows of snow 74, the reflection of the sky was undoubtedly to be taken into the account. "Both causes may, however, operate together," he observed, "and the contrast which a warm yellow light demands may heighten the effect of the blue." This was all his opponent contended.11 With a few such exceptions, the general theory of Goethe with regard to coloured shadows is undoubtedly correct; the experiments with two candles 68, and with coloured glass and fluids 80, as well as the observations on the shadows of snow 75, are conclusive, for in all these cases only one light is actually changed in colour, while the other still assumes the complemental hue. "Coloured shadows," Dr. J. Müller observes, "are usually ascribed to the physiological influence of contrast; the complementary colour presented by the shadow being regarded as the effect of internal causes acting on that part of the retina, and not of the impression of coloured rays from without. This explanation is the one adopted by Rumford, Goethe, Grotthuss, Brandes, Tourtual, Pohlmann, and most authors who have studied the subject.”12 In the Historical Part the author gives an account of a scarce French work, "Observations sur les Ombres Colorées," Paris, 1782. The writer13 concludes that "the colour of shadows is as much owing to the light that causes them as to that which (more faintly) illumines them."

11 Eckermann’s "Gespräche mit Goethe," vol. ii. p. 76 and 280.
12 "Elements of Physiology," by J. Muller, M.D., translated from the German by William Baly, M.D. London, 1839.
13 Anonymous, having only given the initials H. F. T.
14

This opinion of the author is frequently repeated 201 312 591, and as it seems at first sight to be at variance with a received principle of art, it may be as well at once to examine it.

In order to see the general proposition in its true point of view, it will be necessary to forget the arbitrary distinctions of light and shade, and to consider all such modifications between highest brightness and absolute darkness only as so many lesser degrees of light.15 The author, indeed, by the word shadow, always understands a lesser light.

The received notion, as stated by Du Fresnoy,16 is much too positive and unconditional, and is only true when we understand the "displaying" light to comprehend certain degrees of half or reflected light, and the "destroying" shade to mean the intensest degree of obscurity.

There are degrees of brightness which destroy colour as well as degrees of darkness.17 In general, colour resides in a mitigated light, but a very little observation shows us that different colours require different degrees of light to display them. Leonardo da Vinci frequently inculcates the general principle above alluded to, but he as frequently qualifies it; for he not only remarks that the highest light may be comparative privation of colour, but observes, with great truth, that some hues are best displayed in their fully illumined parts, some in their reflections, and some in their halflights; and again, that every colour is most beautiful when lit by reflections from its own surface, or from a hue similar to its own.18

The Venetians went further than Leonardo in this view and practice; and he seems to allude to them when he criticises certain painters, who, in aiming at clearness and fulness of colour, neglected what, in his eyes, was of superior importance, namely, gradation and force of chiaroscuro.19

That increase of colour supposes increase of darkness, as so often stated by Goethe, may be granted without difficulty. To what extent, on the other hand, increase of darkness, or rather diminution of light, is accompanied by increase of colour, is a question which has been variously answered by various schools. Examples of the total negation of the principle are not wanting, nor are they confined to the infancy of the art. Instances, again, of the opposite tendency are frequent in Venetian and early Flemish pictures resembling the augmenting richness of gems or of stained glass20 indeed, it is not impossible that the increase of colour in shade, which is so remarkable in the pictures alluded to, may have been originally suggested by the rich and fascinating effect of stained glass; and the Venetians, in this as in many other respects, may have improved on a hint borrowed from the early German painters, many of whom painted on glass.21

At all events, the principle of still increasing in colour in certain hues seems to have been adopted in Flanders and in Venice at an early period;22 while Giorgione, in carrying the style to the most daring extent, still recommended it by corresponding grandeur of treatment in other respects.

The same general tendency, except that the technical methods are less transparent, is, however, very striking in some of the painters of the school of Umbria, the instructors or early companions of Raphael.23 The influence of these examples, as well as that of Fra Bartolommeo, in Florence, is distinctly to be traced in the works of the great artist just named, but neither is so marked as the effect of his emulation of a Venetian painter at a later period. The glowing colour, sometimes bordering on exaggeration, which Raphael adopted in Rome, is undoubtedly to be attributed to the rivalry of Sebastian del Piombo. This painter, the best of Giorgione’s imitators, arrived in Rome, invited by Agostini Chigi, in 1511, and the most powerful of Raphael’s frescoes, the Heliodorus and Mass of Bolsena, as well as some portraits in the same style, were painted in the two following years. In the hands of some of Raphaels scholars, again, this extreme warmth was occasionally carried to excess, particularly by Pierino del Vaga, with whom it often degenerated into redness. The representative of the glowing manner in Florence was Fra Bartolommeo, and, in the same quality, considered abstractedly, some painters of the school of Ferrara were second to none.

In another Note (par. 177) some further considerations are offered, which may partly explain the prevalence of this style in the beginning of the sixteenth century; here we merely add, that the conditions under which the appearance itself is most apparent in nature are perhaps more obvious in Venice than elsewhere. The colour of general nature may be observed in all places with almost equal convenience, but with regard to an important quality in living nature, namely, the colour of flesh, perhaps there are no circumstances in which its effects at different distances can be so conveniently compared as when the observer and the observed gradually approach and glide past each other on so smooth an element and in so undisturbed a manner as on the canals and in the gondolas of Venice;24 the complexions, from the peculiar mellow carnations of the Italian women to the sun-burnt features and limbs of the mariners, presenting at the same time the fullest variety in another sense.

At a certain distance—the colour being always assumed to be unimpaired by interposed atmosphere—the reflections appear kindled to intenser warmth; the fiery glow of Giorgione is strikingly apparent; the colour is seen in its largest relation; the macchia25 , an expression so emphatically used by Italian writers, appears in all its quantity, and the reflections being the focus of warmth, the hue seems to deepen in shade.

A nearer view gives the detail of cooler tints more perceptibly,26 and the forms are at the same time more distinct. Hence Lanzi is quite correct when, in distinguishing the style of Titian from that of Giorgione, he says that Titian’s was at once more defined and less fiery.27 In a still nearer observation the eye detects the minute lights which Leonardo da Vinci says are incompatible with effects such as those we have described,28 and which, accordingly, we never find in Giorgione and Titian. This large impression of colour, which seems to require the condition of comparative distance for its full effect, was most fitly employed by the same great artists in works painted in the open air or for large altar-pieces. Their celebrated frescoes on the exterior of the Fondaco de’ Tedeschi at Venice, to judge from their faint remains and the descriptions of earlier writers, were remarkable for extreme warmth in the shadows. The old frescoes in the open air throughout Friuli have often the same character, and, owing to the fulness of effect which this treatment ensures, are conspicuous at a very great distance.29

In assuming that the Venetian painters may have acquired a taste for this breadth30 of colour under the circumstances above alluded to, it is moreover to be remembered that the time for this agreeable study was the evening; when the sun had already set behind the hills of Bassano; when the light was glowing but diffused; when shadows were soft—conditions all agreeing with the character of their colouring:31 above all, when the hour invited the fairer portion of the population to betake themselves in their gondolas to the lagunes. The scene of this "promenade" was to the north of Venice, the quarter in which Titian at one time lived. A letter exists written by Francesco Priscianese, giving an account of his supping with the great painter in company with Jacopo Nardi, Pietro Aretino, the sculptor Sansovino, and others. The writer speaks of the beauty of the garden, where the table was prepared, looking over the lagunes towards Murano, "which part of the sea," he continues, "as soon as the sun was down, was covered with a thousand gondolas, graced with beautiful women, and enlivened by the harmony of voices and instruments, which lasted till midnight, forming a pleasing accompaniment to our cheerful repast."32

To return to Goethe: perhaps the foregoing remarks may warrant the conclusion that his idea of colour in shadow is not irreconcileable with the occasional practice of the best painters. The highest examples of the style thus defined are, or were, to be found in the works of Giorgione33 and Titian, and hence the style itself, though "within that circle" few "dare walk" is to be considered the grandest and most perfect. Its possible defects or abuse are not to be dissembled: in addition to the danger of exaggeration34 it is seldom united with the plenitude of light and shade, or with roundness; yet, where fine examples of both modes of treatment may be compared, the charm of colour has perhaps the advantage.V The difficulty of uniting qualities so different in their nature, is proved by the very rare instances in which it has been accomplished. Tintoret in endeavouring to add chiaro-scuro to Venetian colour, in almost every instance fell short of the glowing richness of Titian.35 Giacomo Bassan and his imitators, even in their dark effects, still had the principle of the gem in view: their light, in certain hues, is the minimum of colour, their lower tones are rich, their darks intense, and all is sparkling.36 Of the great painters who, beginning, on the other hand, with chiaroscuro, sought to combine with it the full richness of colour, Correggio, in the opinion of many, approached perfection nearest; but we may perhaps conclude with greater justice that the desired excellence was more completely attained by Rembrandt than by any of the Italians.

15

Leonardo da Vinci observes: "L’ombra è diminuzione di luce, tenebre è privazione di luce.” And again: "Sempre il minor lume è ombra del lume maggiore."—Trattato della Pittura, pp. 274, 299.

N. B. The same edition before described has been consulted throughout.

16
Lux varium vivumque dabit, nullum umbra colorem.
Know first that light displays and shade destroys Refulgent nature’s variegated dies.
Mason's Translation
17 A Spanish writer, Diego de Carvalho e Sampayo, quoted by Goethe ("Farbenlehre," vol. ii.), has a similar observation. This destroying effect of light is striking in climates where the sun is powerful, and was not likely to escape the notice of a Spaniard.
18 Trattato, pp. 103,121,123, 324, etc.
19 lb. pp. 85,134.
20 Absolute opacity, to judge from the older specimens of stained glass, seems to hare been considered inadmissible. The window was to admit light, however modified and varied, in the. form prescribed by the architect, and that form was to be preserved. This has been unfortunately lost sight of in some modern glass-painting, which, by excluding the light in large masses, and adopting the opacity of pictures (the reverse of the influence above alluded to), has interfered with the architectural symmetry in a manner far from desirable. On the other hand, if we suppose painting at any period to have aimed at the imitation of stained glass, such an imitation must of necessity have led to extreme force; for the painter sets out by substituting a mere white ground for the real light of the sky, and would thus be compelled to subdue every tone accordingly. In such an imitation his colour would soon deepen to its intensest state; indeed, considerable portions of the darker hues would be lost in obscurity. The early Flemish pictures seldom err on the side of a gay superabundance of colour; on the contrary, they are generally remarkable for comparatively cool lights, for extreme depth, and a certain subdued splendour, qualities which would necessarily result from the imitation or influence in question.
21 See Langlois, "Peinture sur Verre." Rouen, 1832; Descamps, "La Vie des Peintres Flamands;" and Gessert, "Geechichte der Glasmalerei." Stutgard, 1839. The antiquity of the glass manufactory of Murano (Venice) is also not to be forgotten. Vasari objects to the Venetian glass, because it was darker in colour than that of Flanders, France, and England; but this very quality was more likely to have an advantageous influence on the style of the early oil painters. The use of stained glass was, however, at no period very general in Italy.
22 Zanetti, "Della Pittura Veneziana," marks the progress of the early Venetian painters by the gradual use of the warm outline. There are some mosaics in St. Mark’s which have the effect of flesh-colour, but on examination, the only red colour used is found to be in the outlines and markings. Many of the drawings of the old masters, heightened with red in the shadows, have the same effect. In these drawings the artists judiciously avoided colouring the lips and cheeks much, for this would only have betrayed the want of general colour, as is observable when statues are so treated.
23

Andrea di Luigi, called L’Ingegno, and Niccolo di Fuligno, are cited as the most prominent examples. See Rumohr, "Italienische Forschungen." Perugino himself occasionally adopted a very glowing colour.

The early Italian schools which adhered most to the Byzantine types appear to have been also the most remarkable for depth, or rather darkness, of colour. This fidelity to customary representation was sometimes, as in the schools of Umbria, and to a certain extent in those of Siena and Bologna, the result of a religious veneration for the ancient examples; in others, as in Venice, the circumstance of frequent intercourse with the Levant is also to be taken into the account. The Greek pictures of the Madonna, not to mention other representations, were extremely dark, in exaggerated conformity, it is supposed, with the tradition respecting her real complexion (see D’Agincourt, vol. iv. p. 1); a belief which obtained so late as Lomasso’s time, for, speaking of the Madonna, he observes, “Leggesi perd che fu alquanto bruna." Giotto, who with the independence of genius betrayed a certain contempt for these traditions, failed perhaps to unite improvement with novelty when he substituted a pale white flesh-colour for the traditional brown. Some specimens of his works, still existing at Padua, present a remarkable contrast in this respect with the earliest productions of the Venetian and Paduan artists. His works at Florence differ as widely from those of the earlier painters of Tuscany. This peculiarity was inherited by his imitators, and at one time almost characterised the Florentine school. Leon Battista Alberti was not perhaps the first who objected to it (" Vorrei io che dai pittori fosse comperato il color bianco assai pifi caro che le preziosissime gemme."—Della Pittura, 1. ii.) The attachment of Fra Bartolommeo to the grave character of the Christian types is exemplified in his deep colouring, as well as in other respects.

24 Holland might be excepted, and in Holland similar causes may hare had a similar influence.
25 Local colour; literally, the blot.
26 Zanetti ventures to single out the picture of Tobit and the Angel in S. Marziale as the first example of Titian’s own manner, and in which a direct imitation of Giorgione is no longer apparent. In this picture the lights are cool and the blood-tint very effective.
27
"Mono sfumato, men focoso." — Storia Pitt orient
28 "La prima cosa che de’ colori si perde nelle distance è il lustro, loro minima parte."—Trattato, p. 213; and elsewhere, " I lumi principali in picciol luogo son quelli che in picciola distansa sono i primi che si perdono all’ occhio." — p. 128.
29 A colossal St. Christopher, the usual subject, is frequently seen occupying the whole height of the external wall of a church. We have here an example of the influence of religion, such as it was, even on the style of colouring and practical methods of the art. The mere sight of the image of St. Christopher, the type of strength, was considered sufficient to reinvigorate those who were exhausted by the labours of husbandry. The following is a specimen of the inscriptions inculcating this belief:—
Christophori Sancti speciem quicumque tuetur, Illo namque die nullo languors tenetur.

Hence the practice of painting the figure on the outside of churches, hence its colossal size, and hence the powerful qualities in colour above described. See Maniago, "Storia delle Belle Arti Friulane."

30 The authority of Fuseli sufficiently warrants the application of the term breadth to colour; he sneaks of Titian’s " breadth of local tint."
31
Teneano essi (alcuni maestri) per cosa certa, che in molte opere Tiziano volesse fingere il lume—quale si vede nell’ inclinarsi del sole verso la sera. Oli orizzonti assai luminosi dietro le montagne, le ombre incerte e pifl le carnagioni brunette e roaseggianti delle figure, gl’induceano a creder questo.— Lib. ii.
Leonardo da Vinci observes,
Quel corpo che si troveri in mediocre lume fia in lui poca differenza da' lumi all’ ombre. E questo accade sul far della sera—e queste opere sono dolci ed hacci grazia ogni quality di volto," etc.—p. 336.
Elsewhere, "Le ombre fatte dal sole od altri lumi particolari sono senza grazia." —p. 357; see also p. 247.
32 See "Francesco Priscianese De’ Primi Principii della Lingua Latina,” Venice, 1550. The letter is at the end of the work. It is quoted in Ticozzi’s "Vito de’ Pittori Vecelli,” Milan, 1817.
33 The works of Giorgione are extremely rare. The pictures best calculated to give an idea of the glowing manner for which he is celebrated, are the somewhat early works and several of the altar-pieces of Titian, the best specimens of Palma Vecchio, and the portraits of Sebastian del Piombo.
34

Zanetti and Lodovico Dolce mention Lorenzo Lotto as an instance of the excess of Giorgione’s style. Titian himself sometimes overstepped the mark, as his biographers confess, and as appears, among other instances, from the head of St. Peter in the picture (now in the Vatican) in which the celebrated St. Sebastian is introduced. Raphael was criticised by some cardinals for a similar defect. See "Castiglione, II Cortigiano," 1. ii.

In the same paragraph to which the present observations refer, the authority of Kircher is quoted; his treatise, "Ars magna lucis et umbrae,” was published in Rome in 1646. In a portrait of Nicholas Poussin, engraved by Clouet, the painter is represented holding a book, which, from the title and the circumstance of Poussin having lived in Rome in Kircher’s time, Goethe supposes to be the work in question. The abuse of the principle above alluded to, is perhaps exemplified in the red half-tints observable in some of Poussin’s figures.

The augmentation of colour in subdued light was still more directly taught by Lomaxzo. He composes the half-tints of flesh merely by diminishing the quantity of white, the proportions of the other colours employed (for he enters into minute details) remaining unaltered. See his " Trattato della arte della Pittura," Milan, 1584, p. 301.

35 The finest works of Tintoret-—the Crucifixion and the Miracolo del Servo (considered here merely with reference to their colour,) may be said to combine the excellences of Titian and Giacomo Bassan, on a grand scale; the sparkling clearness of the latter is one of the prominent characteristics of these pictures. Tintoret is reported to have once said that a union of his own knowledge of form with Bassan’s colour would be the perfection of painting. See "Verci Notisie de’ Pittori di Bassano;” Ven. 1775, p. 61.
36 That this last quality, the characteristic of Bassan’s best pictures, was held in high estimation by Paul Veronese, is not only evident from that painter’s own works, but from the circumstance of his preferring to place his sons with Bassan rather than with any other painter. (See "Boschini Carta del Navegar," p. 280.) The Baptism of Sta. Lucilla, in Boschini’s time considered the finest of Giacomo’s works, is still in the church of S. Valentino, at Bassano, and may be considered the type of the lucid and sparkling manner.
37 Reservoirs in which water is collected from various small streams, to work the mines.
38

The author, in these instances, seems to be anticipating his subsequent explanations on the effect of semi-transparent mediums. For an explanation of the general view contained in these paragraphs respecting the gradual increase of colour from high light, see the [note to 69 - sup.]

The anonymous French work before alluded to, among other interesting examples, contains a chapter on shadows cast by the upper light of the sky and coloured by the setting sun. The effect of this remarkable combination is, that the light on a wall is most coloured immediately under a projecting roof, and becomes comparatively neutralised in proportion to its distance from the edge of the darkest shade.

39
The simplest case of the phenomenon, which Goethe calls a subjective halo, and one which at once explains its cause, is the following. Regard a red wafer on a sheet of white paper, keeping the eye stedfastly fixed on a point at its center. When the retina is fatigued, withdraw the head a little from the paper, and a green halo will appear to surround the wafer. By this slight increase of distance the image of the wafer itself on the retina becomes smaller, and the ocular spectrum which before coincided with the direct image, being now relatively larger, is seen as a surrounding ring.—S. F.
Goethe mentions cases of this kind, but does not class them with subjective halos. 30
40 It has been found necessary to follow the authors nomenclature throughout.
41 It has not been thought necessary to copy the plates here referred to.
42 The author more than once admits that this chapter on "Pathological Colours" is very incomplete, and expresses a wish 734 that some medical physiologists would investigate the subject further. This was afterwards in a great degree accomplished by Dr. Johannes Muller, in his memoir “Uber die Phantastischen Gesichtserscheinungen." Coblentz, 1826. Similar phenomena have been also investigated with great labour and success by Purkinje. For a collection of extraordinary facts of the kind recorded by these writers, the reader may consult Scott’s Letters on Demonology and Witchcraft.43 The instances adduced by Muller and others are, however, intended to prove the inherent capacity of the organ of vision to produce light and colours. In some maladies of the eye, the patient, it seems, suffers the constant presence of light without external light. The exciting principle in this case is thus proved to be within, and the conclusion of the physiologists is that external light is only one of the causes which produce luminous and coloured impressions. That this view was anticipated by Newton may be gathered from the concluding "query" in the third book of his Optics.
43 See also a curious passage on the beatific vision of the monks of Mount Athos, in Gibbon, chap 63λ .
Seabeck's Footnotes
a

Leonardo da Vinci observes that "a light object relieved on a dark ground appears magnified;" and again:

Objects seen at a distance appear out of proportion; this is because the light parts transmit their rays to the eye more powerfully than the dark. A woman's white head-dress once appeared to me much wider than her shoulders, owing to their being dressed in black.2

It is now generally admitted that the excitation produced by light is propagated on the retina a little beyond the outline of the image. Professor Plateau, of Ghent, has devoted a very interesting special memoir to the description and explanation of phenomena of this nature. See his 'Mémoire sur l'Irradiation,' published in the 11th vol. of the Transactions of the Royal Academy of Sciences at Brussels.3

b The duration of ocular spectra produced by strongly exciting the retina, may be conveniently measured by minutes and seconds; but to ascertain the duration of more evanescent phenomena, recourse must be had to other means. The Chevalier d'Arcy (Mem. de l'Acad. des Sc. 1765) endeavoured to ascertain the duration of the impression produced by a glowing coal in the following manner. He attached it to the circumference of a wheel, the velocity of which was gradually increased until the apparent trace of the object formed a complete circle, and then measured the duration of a revolution, which was obviously that of the impression. To ascertain the duration of a revolution it is sufficient merely to know the number of revolutions described in a given time. Recently more refined experiments of the same kind have been made by Professors Plateau and Wheatstone.
c Cases of this kind are by no means uncommon. Several interesting ones are related in Sir John Herschell’s article on Light in the Encyclopædia Metropolitana. Careful investigation has, however, shown that this defect of vision arises in most, if not in all cases, from an inability to perceive the red, not the blue rays. The terms are so confounded by the individuals thus affected, that the comparison of colours in their presence is the only standard.
TheoryOfColor.org's Footnotes
α Goethe explains his "harmony" in paragraph 61
β In John Wall's book: Experiments, and Observations on the Malvern Waters, he is only able to see blue light emanating from the water is examining.
γ These footnotes are now separated and displayed as Seabeck's Footntoes.
δ

Benvento writes in the Introduction of his Autobiography:

The second of these examples is more curious and far more confirmatory of his truth. After those half delirious experiences in the dungeon of S. Angelo, when he saw visions and thought that angels ministered to his sick body, he fancied himself under God's special guidance. As a sign of this peculiar grace, he relates the following circumstance:

Since that time till now an aureole of glory (marvellous to relate) has rested on my head. This is visible to every sort of men to whom I have chosen to point it out; but these have been very few. This halo can be observed above my shadow in the morning, from the rising of the sun for about two hours, and far better when the grass is drenched with dew. It is also visible at evening about sunset. I became aware of it in France, at Paris; for the air in those countries is so much freer from mist that one can see it there far better manifested than in Italy, mists being far more frequent among us. However, I am always able to see it, and to show it to others, but not so well as in the country I have mentioned.

Critics have taken for granted that this is a mere piece of audacious mendacity meant to glorify himself, whereas it is really the record of a very accurate but misinterpreted observation. Any one who walks abroad in grassy places when the light is low, as at sunrise or at sunset, can satisfy himself that his shadow cast on dewy sward is surrounded with a rim of glory like a lunar rainbow. But if he goes with companions, he will not see their shadows encircled with the same light, because his own body is the point which focusses the diffused rays.ε He, therefore, might well imagine that the aureole is given to himself alone; and, in order to exhibit it, he must make his comrade take a place behind him, where the halo becomes at once visible to both. Long before I attended to the above passage in Cellini, I noticed this phenomenon, and pointed it out to friends, finding that some of them were too deficient in powers of observation to perceive it, while others at once recognised the singular and beautiful effect. What makes the example interesting for the light it casts on Cellini's habit of mind is that he starts by saying the aureole surrounds his head, and then very ingenuously proceeds to tell us that it only surrounds the shadow of his head at certain times and in certain places. Those times and places are just what the experience of one who has observed the same phenomenon would lead him to expect. Again, he sets up a false theory to explain why he could see it better in France than in Italy. It is not that there is more mist in the latter than the former country, but that low-lying humidity of atmosphere and heavy dews on deep grass are favourable to the production of the appearance, and these conditions may be met with more frequently in a country like France than in the provinces of Middle Italy. It was upon the Alpine meadows, where I am now writing, at the season of early autumn frosts, that I first noticed it; and I can predict with some confidence when it is pretty certain to be reproduced. In my opinion, the very hesitancies of Cellini in this test-passage are undesigned corroborations of his general veracity. A man who deliberately invents something to glorify himself and mystify the world does not go about his work in this fashion. He does not describe a natural phenomenon so exactly that all the limiting conditions, which he regarded as inexplicable imperfections in the grace conferred upon him, shall confirm the truth of his observation.

ε

On the appearance of this passage in the Fortnightly Review for January, I received a communication from H. D. Pearsall, Esq., of 3 Cursitor Street, expressing some interest in my account of Cellini's aureole. He says:

I observed the phenomenon some years ago in India, and the attendant circumstances were such as you mention. It is curious, as illustrating the want of observation of most people, that I have never yet met with any one but yourself who had observed it.

In explanation of the aureole he adds:

It appeared to me that the cause was simply the reflection of the direct rays of the sun from the wet surface of the blades of grass. The reason why a spectator at one side cannot see it would, therefore, not be that the illuminated person's body focussed the diffused rays, but simply the direct consequence of the law of reflection of light (angle of incidence = angle of refraction), so that the reflected rays would reach the eye of the object, but not that of any person at a little distance to one side. The aureole never extended lower than my shoulder, evidently for the same reason.

This explanation is so obviously superior to that suggested by my own vague and unscientific phrase in the text, that I am grateful for the permission to report it in Mr. Pearsall's own words. It is worth adding, perhaps, that when the object finds himself at a considerable distance from the reflecting surface of wet grass, as when, for instance, he is driving in a carriage above a grassy meadow, the aureole will extend somewhat lower than his shoulder. This I have observed.

ζ

Julia Pardoe writes in The Life and Memoirs of Marie de Medici, Queen and Regent of France:

That such was actually the case is proved by de Thou, who relates an extraordinary speech made by the King at the Louvre, in 1599, on the occasion of the promulgation of the Edict of Nantes, to the deputies of the Parliament of Paris; in the course of which he declared that, twenty-six years previously, when he was residing at the court of Charles IX., he was about to cast the dice with Henry of Lorraine, Duke de Guise, his relative, amid a large circle of nobles, when at the instant in which they were prepared to commence their game, drops of blood appeared upon the table, which were renewed without any apparent agency as fast as they were wiped away. Each party carefully ascertained that it could- not proceed from any of the individuals present; and the phenomenon was so frequently repeated, that Henry, as he averred, at once amazed and disturbed, declined to persevere in the pastime, considering the circumstance as an evil omen.f Whatever may be the opinion of the reader as to the actual cause of this apparent prodigy, it is at least certain that it was verified by subsequent events; and well as the extraordinary and multiplied prophecy that the King himself would meeet his death in a coach.
η Shady, Shaded
θ Rumfort, no doubt refers to Benjamin Thompson, whom was also knon as Count Rumford, and whom created a photometer simlilar to the Lambert-Bouguer photometer.
ι Johann Georg Büsch is likley the best known Büsch of the day, but it remains unclear this is the figure that Goethe is refering to.
κ Leopold Schefer was a famous poet duing the day, but it remains unclear if this is who Goethe is referencing.