Dr. Kim H. Veltman
Definitions and Categories
2. Light and Sight
3. Categories of Light
4. Categories of Shade
6.1 Black and White
6.2 Simple Colours
6.3 Compound Pigment Colours and Compound Coloured Lights
6.4 Light and Colour
6.5 Light and Beauty
6.6 Darkness and Colour
6.7 Colour Conclusions
Leonardo's fascination with light and shade relates both to his painting practice and his optical theory. As has been shown elsewhere (Vol. One, Part Three), light and shade, or chiaroscuro as he terms it, makes possible the drawing of muscles (CU50, TPL42, 1505-1510), provides a sense of relief or depth in objects (A96v, BN 2038 16v, CU847, TPL667, 1492, CU844, TPL716, 1508-1510) and makes figures appear life-like (A100r, BN 1038 20r, 1492). For this reason he makes chiaroscuro the second principle of his painting practice (CU4, TPL5, 1500-1505), and describes it as the "excellence" of that science (CU840, TPL671, 1508-1510).1
He believes that the properties of light are analogous to those of sight. This is why his physics of light and shade involves many themes that relate directly to his theories of vision. Hence it will be useful to examine these light-sight analogies before considering his definitions and categories of light, shade, lustre and darkness. He also makes reference to seven books on light and shade. Richter, in the Literary Works make a rough attempt at reconstructing six of these books.2 Pedretti has taken this one step further.3 We shall show, however, that Leonardo's outline can be taken more seriously; that all seven books, plus an eighth on movement can be reconstructed and that his studies in this domain involve a much more coherent structure than has hitherto been imagined. Moreover, these studies reveal an unexpected amount of systematic experimental research.
In a subsequent chapter it will be shown that his studies of the camera obscura go hand in hand with these studies on light and shade. For instance, he makes systematic studies of different sizes and shapes of apertures in order to discern more complex properties of light and shade. He demonstrates that the image in a camera obscura sometimes resembles the aperture, and at other times assumes the shape of the original light source. He also discovers that, under certain conditions, the boundaries between light and shade are fully obscured, leaving a spectrum of gradations. In his early writings he claimed that light and shade were more difficult than design (disegno, A81r, BN 2038 1r). His new findings convince him that the boundaries between light and shade are most difficult of all (CU106, TPL121, 1505-1510).
Having considered his studies of light and shade (part two), it will be shown how these studies serve as a basis for his physiology of vision (part three): how he compares the aperture of a camera obscura with the aperture of an eye, and how his work on gradations of light and shade influences his claims that the eye cannot perceive boundaries clearly.
2. Light and Sight
Leonardo's conviction that the properties of light and sight are fully analogous explains the close links between his physics of light and shade and physiology of vision. His earliest extant reference to this analogy occurs on W19147-19148v, (K/P 22v, c.1489-1490) where he notes that: "
Light does the same, because in the effects of its lines and maximally in the works of perspective it is very similar to the eye." Some two years later he explores this theme at length on CA204vb (c.1492):
Light in the function of perspective is no different from the eye. The reason that light is no different from the eye as concerns occluding that which is behind the first object, is this: you know that as concerns speed of motion and the concourse of straight lines, the visual ray and the luminous ray are the same....
Directly following he gives a demonstration:
For example, if you place a coin...near the eye, that...space which occurs between the coin and the extremity of the site, the more that it is capable of a greater interval, the greater will be that part of the extremity of the site that is not seen by the eye and [hence] the closer that the coin is to the eye, the more will the extremity of the site be occluded.
He expands on this in the next paragraph:
The same will occur in light, because in bringing a coin nearer or further from this light you will see the shadow increasing or decreasing on the opposite wall. And if you wish an example, do it in this form: have placed in a room many bodies of various objects. Then take in your hand a long pole with charcoal at the end and with this mark off on the ground and on the walls...all the [projected] boundaries of the panels which appear beyond the [actual] boundaries of the panels.
In the right-hand margin alongside this he writes the headings: "On the eye," and "On light." In the paragraph that follows his description continues:
Then at this same distance and height take a light and you will observe that the shadows of the said bodies occupy as much of the wall, as is that part which finds itself included within the marks made by the charcoal at the end of the stick.
Next he describes a related demonstration:
If you wish to see clearly a similar experiment place a lamp at the head of a table...then go backwards somewhat and you will observe all the shadows of the objects which are between the wall and the light stamped by shadow...in the form of the objects...and all the lines of their length directed to the point where the light is.
Then bring your eye nearer to this light, producing such shadow with the edge of a knife so as not to offend the eye and you will see all the objects positioned opposite without shadow and the shadows which were on the panels of the eye will be occluded at the eye by the interposed objects.
In short, the area thrown into shadow by candlelight coincides with the area occluded by the same object as a result of the visual angle. He develops this idea on CA241vd (1508-1510):
In all the functions of shade spherical light is as the eye in its visual power, because one opaque sphere interposed between the eye and a panel will occlude as much of the light on that panel as would the eye.
He pursues this analogy on CA195v (c.1510):
A window does the same on each side whether above or below and likewise on one side as one the other where it borders on the dark wall.
And the species that enter the pupil do the same and they are thrown to the right and left, intersected behind the interposed object.
This close analogy between geometrical light rays and visual rays explains (a) why various folies with notes on the physics of light and shade also deal with the physiology of vision and (b) why he continues to use "perspective" in its mediaeval sense meaning "vision" as, for example, on W19037v (K/P 81v, 1489-1490), when describing his anatomical programme, he refers to "perspective, through the action of the eye" or on CA119va (c.1492) where he makes the heading: "Premium to perspective: that is, on the function of the eye." Leonardo takes this analogy further. In his mind the geometry of visual rays, the geometry of rays of light and shade and the geometry of rays of linear perspective are all equivalent. Hence his claim in a draft note on BM103v (1490-1495) that "all the functions of lights are similar to those of the eye as concerns the perspective of painters." On A103v(BN 2038 23v) he claims that in "all cases of linear perspective it is similar to light." For this reason he is usually not concerned with distinguishing clearly between perspective (a) in the sense of "optics" and (b) in the sense of "linear perspective," as is evidenced by his definition of perspective on A3r (1492):
as a demonstrative reason by means of which experience confirms that all things send their similitudes to the eye by pyramidal lines.
For the same reason, he deals interchangeably with problems of vision, linear perspective, and light and shade with respect to anamorphosis in his treatise on perspective on A36v-A42v analysed earlier (see Vol. 1, Part I:2 ). Moreover, this light-sight analogy explains why a number of folios dealing with rays of light from the sun also contain notes on vision (see below pp. figs. ). Indeed, once we understand that analogy is a key to Leonardo's organization, much of the apparent confusion of his notebooks disappears.
3. Categories of Sight
Leonardo has practically no definitions of light. He calls light the chaser of darkness of CA116rb (1492). He notes that light makes objects evident (dimostra), whereas shade hides them (A102r, BN 2038 22v, 1492). He does not dwell on the metaphysics of light. The importance he attaches to the subject is, nonetheless, clear from the opening passage of Pecham's Perspectiva communis that he copies in translation on cA203ra (1492).
Among the study of natural considerations, light delights its contemplators most. Among the great things of mathematics the certainty of the demonstrations raises most sublimely the mind of the investigators. Hence perspective is to be proposed above all the traditions and humane disciplines, in the domain of which the luminous ray, complicated by the modes of demonstrations, finds the glory of both mathematics and physics, decorated by the flowers of each.
Leonardo is more interested in various categories of light. In the Mediaeval optical tradition one had distinguished between primary (direct) and secondary (reflected light.4 There had also been a distinction between lux (A102r, BN 2038 22r, 1492). He also makes a distinction between primitive and derived lights which, according to his definition on C16v (1490), would correspond to the mediaeval terms primary and secondary light: "That light is said to be primitive which primarily lights umbrous objects and derived is said to be that which is reflected from those parts."
On CU158 (TPL157, C.1492) he reformulates this definition, now substituting "original" for "primitive":
...lights are of two kinds (nature): one is called original, the other derivative. Original I claim to be that which derives from the flame of a fire or from the light of the sun or the air.
Derived light is reflected light.
In another passage on BM171r (c.1492) he reverts to his earlier terms, primary and derived, but now defines them somewhat differently under the heading:
How lights are of two kinds, the one separate, the other joined to bodies.
Separate is that which illumines the body: joined is that part of the body illumined by that light. The one light is called primitive, the other, derived. And likewise shadows are of 2 kinds: the one primitive, the other derived shadow. Primitive is that which separates itself from bodies, carrying in itself the form of its cause to the panels of walls.
He returns to this distinction between primitive and derivative light on CA116rb (c.1498 or 1495-1497): "Primitive light is that which is the cause of illuminating umbrous bodies. And derived lights are those parts of bodies...illuminated by the first light."
Alberti in his On Painting had distinguished between light from the stars, i.e. sun, moon, enus, etc. and light from fires.6 He had also mentioned reflected light. Leonardo takes these distinctions further. In an early note on BM 170r (1492), he distinguishes simply between free and restricted light (figs. ):
How there are 2 different lights, the one is called free and the other restricted. The free [light] is that which freely illumines bodies, restricted is that which illumines bodies all the same through some aperture or window.
On A109r (BN 2038 29r, 1492) he develops this into a threefold distinction:
First you will treat of the lights made by windows, to which you will give the name restricted air; then you will deal with lights of the countryside, to which you will give the name free light and then you will deal with the light of luminous bodies.
This evolves into a fourfold distinction on G3v (1515, cf. CU598, TPL663, c. 1510), under the heading:
The lights which illuminate opaque bodies are 4 kinds, that is, universal, as is the air which is within our horizon, and particular, as is that of the sun or of a window or a door or some other space. And the third is reflected light and then there is a 4th, which passes through transparent things, such as cloth or paper or the like, but not transparent like glass or crystal or other diaphanous bodies, which have the same effect as if nothing were interposed between the umbrous body and the light which illuminates it and of these [various kinds of light] we shall speak distinctly in our discourse.
Elsewhere he is content to omit mention of transparent light and limit his discussion to three kinds as on CU866 (TPL754, 1508-1510):
On giving the necessary lights to illuminated objects in accordance with their sites.
One needs to have great respect for the lights accommodated to the things illuminated by them since, in a given story, there may occur parts which are in the countryside in the universal light of the air and other which are in porticoes, which are a mixture of particular and universal light and others in particular light, such as in houses which receive light from a single window.
Of these three kinds of light, for the first it is necessary to take the lights of large fields by the fourth of the first which states "such is the proportion of size to size on the part of illuminated bodies as is that of the size to size of the bodies illuminating them." And again of those, namely, which require the reflections from one body to another, where the light enters through narrow places among those bodies illuminated by universal light, because with the lights which penetrate between bodies close to one another, the same happens as with the lights which penetrate the windows and doors of houses, which we term particular lights.
And which shall also make the necessary remarks about this in its proper place.
A late reference to this threefold distinction is found on E3v (c.1513-1514) under the heading of:
Of the 3 kinds of lights which illuminate opaque bodies.
The first of the lights with which opaque bodies are illuminated is said to be particular, and this is the sun or some other light of a window or a fire. The second is universal as happens in times of cloud or fog or the like. The third is compound, that is in the evening or in the morning when the sun is entirely beneath the horizon.
This third variety of light here mentioned he had described in more detail on CU593 (TPL558, 1508-1510) in a passage entitled:
What is the difference between compound light and compound shade?
Compound shade is that which participates more in the umbrous body than in the luminous body. Compound light is that which participates more in the luminous than in the umbrous. Hence, we shall state that compound shade and light take their name from that in which it participates most, namely, that if an illuminated object sees more shade than light, that it is said to be invested with compound shade and if it is invested with more from the luminous body than from the umbrous one then, as we said, it is called compound light.
Hence Leonardo considers various categories of light: primitive (separate) and derived (joined); universal (free), particular (restricted), reflected, translucent and compound. As we shall see some of these categories recur in his discussion of shade.
4. Categories of Shade
Pecham had claimed that "shadows are diminished light."7 "Shade, writes Leonardo on C14v (1490-1491), "is a diminution of light." He returns to this definition in a paraphrase on W19152v (K/P118v, C.1508-1510):
Shade is diminished light mediated by the opposition of an opaque body.
Shade is the substitution of the luminous ray that has been intersected by an opaque (body].
On W19076r (K/P167r, c.1513) this definition becomes the first in a series of alternatives:
Shade is the diminution of light and of darkness and it is interposed between these darknesses and lights.
Shade is of infinite obscurity and of infinite diminution of this obscurity.
The beginnings and ends of shade extend themselves between lights and darknesses and [it] is of infinite diminution and infinite augmentation.
Shade is a pronouncement by bodies of their shapes.
The shapes of bodies will not give knowledge (notitia) of their quality without shade.
He returns to the first of these definitions on E32v (1513-1514, CU580, TPL550a, 1513-1514): "Shade is diminution of light." A variant of this basic definition is found on A102r (BN 2038 22r, CU577, TPL549c, 1492): "Shade is privation of light and only the opposition of dense bodies opposite luminous rays: shade is of the nature of darkness...." One of these definitions he repeats on CA116rb (c.1498 or 1495-1497): "Shade is privation of light." On CU604 (TPL660b, 1508-1510) he combines two of these basic definitions: "Shade is a diminution or a privation of light." At other times as on Mad II 25r (c.1503-1504) he defines darkness as "a privation of light" claiming that "shade is an alleviation of light. And there is no darkness where there is not some exhalation of air." He returns to this formulation on CA207ra (c.1508-1512):
Darkness is a privation of light.
And shade is an alleviation of this light.
Shade is a mixture of darkness with light.
Shade is an alleviation of darkness and light.
A related version occurs on CU578 (TPL665, 1508-1510): "Darkness is a privation of light and light is a privation of darkness. Shade is a mixture of darkness with light." On A102r (BN 2038 22r, CU577, TPL549, 1492), he describes shade as being: " of greater power than light, because this prohibits and deprives objects entirely of light, and light can never hide the shade of bodies, that is, dense bodies." On CU582 (TPL556, 1508-1510) he provides yet another definition: "shade is said to be that where no part of the luminous body or illuminated body can see." On CA207ra (1508-1510) he drafts two further definitions:
Shadow in opaque bodies is percussion of the species of dark bodies.
Shadow is a mixture of bright and dark and of that much more or less darkness to the extent that the bright which mixes itself with it is of greater or less power.
These he crosses out and writes anew: "Shadow is a mixture of bright and dark and is of that much more or less darkness as the bright with which...it mixes itself will be of greater power." As in the case of light Leonardo considers various categories of shade. A straightforward solution is given on CU597 (TPL569, 1508-1510) in a passage entitled:
How many sorts of shade are there?
There are three sorts of shade of which one is born from a particular light such as the sun, moon or a flame. The second is that which derives from a door, window or other aperture, from whence one sees a large part of the sky. The third is that which is born from universal light, such as the light of our hemisphere when it is without sun.
In the passage on BM171r (c.1492) cited above it was noted that just as he distinguishes between primitive and derived light, so too does he distinguish between primitive and derived shade (fig. ). In the extant notes this distinction first occurs on Triv 11v, 29r (c.1487-1490). He returns to it on C14v (1490) where he lists a number of basic definitions:
Primitive shade is that which attached to umbrous bodies.
Derivative shade is that which is detached from umbrous bodies and passes through the air.
Repercussed shade is that which is surrounded by an illuminated wall.
Simple shade is that which does not see any part of the light that causes it.
Simple shade begins in that line which parts from the boundaries of the luminous bodies ab [fig. 174).
Fig. 174: Illustration of simple shade on C14v.
In the introduction to his books on light and shade on CA250ra (c.1490) Leonardo drops the term "primitive" and refers instead to: "Original shadows since they are the first shadows which invest the bodies to which they are attached." He then goes on to note that:
from these original shadows umbrous rays result which go spreading through the air and are of as many kinds as are the varieties of the original shadows, whence they derive. And for this reason I call them derived, because they are born from other shadows.
He pursues these distinctions on A102r (BN 2038 22r, 1492) now referring to primitive shade as joined and derived shade as separate (figs. ):
What is the difference between shade joined with bodies and separated shade.
Joined shade is that which never parts from the illuminated bodies, as would be [the case with] a ball which, standing in the light, always has one part of itself occupied by shade, which never divides itself through a change in position made by this ball. Separate shade can exist and not be created by the body. Let us suppose that this ball is one braccia distant from a wall and from the opposite side is in light. The said light will send to the given wall just so much dilation of shadow as is that which finds itself on the part of the ball which is facing the wall. That part of the separate shade which does not appear, is when the light is below the ball, [such] that its shade goes towards the sky, and not finding resistance in its path, is lost.
On CA116rb (1498 or 1495-1497) this theme is taken up anew in a draft:
Primitive shade is that part of the bodies which cannot be seen by light.
Derived shade...is only the percussion...of umbrous...rays.
Accompanying this passage is a diagram (fig. ) illustrating primitive and derived light and shade. Some years later he makes a passing reference to this distinction on CU585 (TPL570, 1505-1508): "The species of shadows are of two sorts, of which one is called primitive and the other derived." Almost as cursory is a passage on CU584 (TPL552, 1508-1510) entitled:
On shadow and its divisions.
The shadows in bodies are generated from dark objects opposite these bodies and they are divided into two parts of which the one is called primitive and the other derived.
In the late period he returns once more to these terms on E32v (1513-1514, cf. TPL553a, c.1508-1510):
Shade is divided into two parts of which the first is said to be primitive shade and the second is derived shade.
Primitive shade always serves as a basis of derived shade.
The boundaries of derived shade are rectilinear.
On C14v (1490) he had referred to repercussed shade. On E32r (c.1513-1514) he returns to this concept, now calling it something else: " On corrupt shadows. Corrupt shadows are said to be those which are seen by a white wall or other luminous bodies." On CU759 (TPL573, 1505-1508) he subdivides the category of derived shade, in a passage headed:
What are the varieties of derivative shade?
The varieties of derivative shade are of two sorts, of which the first is mixed with the air which stands opposite the primitive shade and the other is that which percusses at the object which meets this derived shade.
As will be seen in the next chapter he further subdivides the first of these categories into shadows that increase with distance, those that remain constant and those that decrease with distance (figs. ). These basic categories are summarized in our Chart. 5. On CU588 (TPL572, 1505-1508) he considers another subdivision of primitive shade (figs. ):
In how many ways does primitive shade vary?
Primitive shade varies in two ways, of which the first is simple and the second is compound.
Simple is that which faces a dark place and for which such shadow is tenebrous. Compound is that which sees a place illuminated with various colours, such that this shadow will mix itself with the species of the colours of the objects positioned opposite.
He returns to this distinction between simple and compound shade on BM248v (c.1508): "Simple shade is that which does not see any luminous body. Compound shade is that which is illuminated by one or more luminous bodies." On CU590, (TPL553, 1508-1510) he again describes these two kinds of shade in a passage headed:
On two species of shade and in how many parts they are divided.
The species of shade are divided into two parts, the one of which is said to be simple, and the other compound. Simple is that which is caused by a single light on a single body. Compound is that which is generated by a number of lights on a same body or by a number of lights on various bodies.
In the passage immediately following on CU591-592 (TPL553a-b, 1508-1510) he divides simple shade further:
Simple shade is divided into two parts, that is, primitive and derivative. Primitive is that which is joined at the surface of the umbrous body. Derivative is that shade, which parts from the aforesaid body and passes through the air, and if it finds resistance it comes to rest at the place where it repercusses, with the shape of its own base.
And the same is said of compound shade.
Chart 5: Classifications of kinds of shade in Leonardo's notes.
In other words, simple and compound shade have here become generic terms to which the categories primitive and derived are now subordinate, (see Chart 5). He returns once more to this basic distinction between simple and compound shade on CU582 (TPL557, 1508-1510):
What difference is there between simple and compound shade?
Simple shade is that where no part of the luminous body can see. And compound shade is that where, between the simple shade a part of the derivative light mixes.
In addition to these categories of light and shade he also provides basic definitions of lustre, colour and darkness. Each of these will be considered in turn.
Leonardo distinguishes between light and lustre in an early note on A113v (BN 2038 32v, 1492):
What difference is there between light and lustre and how lustres are not among the number of colours and [a lustre] is always whitish and it originates on the extremities of bodies basked [in light]. Light is of the colour of the object whence it originates such as gold or silver or a similar thing.
A pithy definition of lustre occurs on CU769 (TPL664, 1508-1510) under the heading:
On illumination and lustre.
Illumination is participation of light, and lustre is the mirroring of this light.
Fig. 175: Illustration of lustre on G10r.
On CU774 (TPL775, 1508-1510) he develops this distinction between lights and lustre under the heading:
What is the difference between lustre and light?
The difference that there is between lustre and light is that lustre is always more powerful than light and light is of a greater quantity than lustre. And lustre moves with the eye and with its cause, and with the one and the other, but a light is fixed at a given place, as long as the cause which generates it is not removed.
He returns to this theme on E31v (CU780, TPL776, 1513-1514):
Of light and lustre.
What difference is there between light and the lustre which shows itself on the terse surfaces of opaque bodies?
The lights which are generated on the smooth (terse) surfaces of opaque bodies will be immobile in immobile bodies even if the eye of these viewers moves. But the lustres will be on the same bodies in as many parts of its surface as are the sites where the eye moves.
In another late passage on G10r (c.1510-1511) he refers to lustre as an "accident" (fig. 175 ):
On the shadow of a leaf.
Sometimes a leaf has 3 accidents, that is, shadow, lustre and transparency, as when the light is at n on the folio s and the eye at m which sees a illuminated, b in shadow and c transparent.
Elsewhere in this same treatise, on G24r (CU949, TPL886, c.1510-1511) he again refers to lustre as an "accident" but this time of colours:
Of the accidental colour of trees.
The accidental colours of the leaves of trees are 4, that is, shadow, light, lustre and transparency.
In Antiquity the problem of colour had been linked with philosophical debates concerning the visual process. Leon Battista Alberti, in his On Painting (1434), is aware of these philosophical debates but consciously avoids them.8 He alludes to theory, but emphasizes practice.
6.1 Black and White
With respect to black and white, for instance, Alberti notes that "the painter ought to be persuaded that white and black are not true colours but alterations of other colours"9 and at the same time treats them as if they were colours. Leonardo inherits this ambiguous approach which theoretically rejects and practically accepts black and white as colours. On CU783 (TPL692, 1508-1510), for example, he mentions in passing "if it can be said of white that it is a colour. On CU739 (TPL699, 1508-1510), he notes that "neither white nor black are colours." On F75r (CU204, TPL247, 1508), he goes further and sets out to show "why white is not a colour" (see below p. ). This leads him, on CU205 (TPL215, 1505-1510), to discuss white as the most receptive of colours because it is empty:
What is that surface that is most receptive of colours?
White is more receptive of the colours than any other surface of any body which is not mirrored.
This is proved, saying, that every object which is empty is capable of receiving that which the objects which are not empty cannot receive. For this [reason] let us say that white is empty or, if you wish to say, deprived of any colour, it being illuminated by the colour of some luminous body it will participate more in this luminous body than would black which in its use is like a broken vase which is deprived of every capacity of a given thing.
On F23r (1508) he notes, in passing, "no white or black is transparent."
6.2 Simple Colours
Nonetheless, in practical terms, he accepts black and white as simple colours, as on CU176 (TPL254, 1508-1510) where he lists six:
On the colours which result from the mixture of other colours, which call themselves secondary species.
The simple [colours] are six, of which the first is white, although some philosophers do not accept either white or black among the number of the colours, because the one is the cause of colours and the other is the privation [thereof]. Yet since the painter cannot do without these we shall place it among the number of the others and we shall say that in this order white is the first of the simple, and yellow is the second and green is the third, and azure is the fourth, and red is the fifth and black is the sixth.
These simple colours he links with various elements:
And we shall let white stand for light, without which no colour can be seen, and yellow for earth; green for water; azure for air, and red for fire because there is no material or size where the rays of the sun have to percuss and consequently to illuminate.
His equivalents bear comparison with those of Alberti10, although the two authors disagree on the colour of earth (Chart 6). Leonardo makes a further list of simple colours on CU178 (TPL213, 1505-1510). Instead of six, he now mentions eight:
Simple colours I call those which are not compound, nor can they be composed through a mixture of other colours.
Black, [and] white, even if these are not placed among the colours, because the one is darkness and the other is light, that is, the one is privation and the other generates, I do not want to leave them behind for this reason, because in painting they are the principal [colours] since painting is composed of shade and light, that is chiaro-scuro.
After black and white follow azure and yellow, then green and leonine, that is, tan, or if you wish ochre, then morello and red. And these are the eight colours, and there are no more in nature.
6.3 Compound Pigment Colours and Compound Coloured Lights
He goes on to describe how these basic colours can be mixed to produce further colours:
Chart 6: Basic elements and equivalent colours according to Alberti and Leonardo
With these I begin mixtures, first white and black, then yellow and black, yellow and red, and since I here lack paper, I will wait to make such distinctions in my work with a long process which will be of great use and also most necessary. And such a description will be intermediate between the theory and practice of painting.
This leads to instructions concerning more complex mixtures of pigments (see below pp. ). Meanwhile, by 1492, he is studying how light passing through coloured glass becomes a different colour, as on CA126ra where, in connection with a camera obscura (fig. 156, see above pp. ), he notes: "how the point is cause of the base: ...put a coloured glass in front of a light and you will see the base tinged in this [colour]." On W19151v (K/P118v(B), 1508-1510) he describes how sunlight passing through both an azure and a yellow pane of glass produces a green light (see below pp. ). In such experiences he finds a new demonstration for the production of compound colours, as, for instance on CU176 (TPL254, 1508-1510):
If you wish with brevity to see the variety of all the compound colours, take pieces of coloured glass and through these look at all the colours of the countryside which are seen beyond this and thus you will see all the colours of things which are behind such a window and you will see what is the colour which you thereby improve or spoil.
This leads to a description of what happens in the case of various colours of glass:
When the aforesaid glass is of a yellow colour, I say that the species of the objects which pass to the eye through this colour can either become worse or better. And this deterioration of such colour will occur in azure and black and white more than in any of the others and the amelioration will occur in yellow and green more than in any of the others. And thus you will go glancing with the eye, the mixtures of colours which are infinite and in this way you will make a choice of colours of new inventions of mixtures and compounds. And the same is done with two panes of glass of different colours positioned in front of the eye and thus you can carry on on your own.
As a result of such experiences he revises his list of simple colours. Azure and green, which he had at first described as simple (CU176, 178), he describes as compound on CU177 (TPL255, 1505-1510):
Azure and green are not simple per se because azure is composed of light and darkness, as is that of the air, that is, most perfect blackness and most bright white.
Green is composed of a simple and a compound colour, that is it is composed of azure and green.
6.4 Light and Colour
Such experiences make him ever more aware of the extent to which colour is determined by the intensity and colour of nearby light and shade. In the early period, as on CU208 (TPL259b, 1482), he believes that a colour can only be true, if it is not seen by other shadow or lustre:
Of true colour.
The true colour of some body will be shown in that part which is not occupied by any quality of shadow, nor of lustre, if it is a polished body.
He restates this idea on CU725 (TPL694e, 1508-1510):
When a particular light illuminates its object, which object has opposite it some object illuminated by the same light which is of a bright colour, then a counter-light is produced that is, the reflection or true reverberation.
That part of the reflected light which partly invests the surfaces of the bodies will be that much less bright than the part illuminated by the air to the extent that this is less bright than the air.
Meanwhile he is also exploring the conditions for true shade as, for example, on CU803 (TPL703, 1508-1510):
What is, in itself, the true shade of colours of bodies.
The shade of bodies should not participate in another colour other than that of the body where it touches. Therefore, since black is not included among the number of the colours, from it are taken the shadows of all the colours of bodies with more or less darkness which is more or less required in its place, never losing entirely the colour of this said body except in the shadows included within the boundaries of the opaque body.
On CU197 (TPL203, 1505-1510) he reconsiders the conditions required for true colour:
How nothing shows its true colour if it does not have light from another colour [that is] the same.
No colour will ever show its proper colour if the light which illuminates it is not entirely of this colour.
That which has been said is shown in the colour of vestments of which the illuminated folds reflect and give light to the folds opposite [and] make them show their true colour. A leaf of gold does the same in giving light to the other and it does the contrary of taking light from another colour.
He pursues this question of true colours on CU799 (TPL816, 1508-1510):
The true colours of the shades and lights of any body are such that the walls of the habitations where such a body is found are the colour of the body which is enclosed inside them and such that the light of the paper window covering, which illuminates such a habitation, is also the colour of this enclosed body and thus the habitation will generate sun only with its umbrous parts on the enclosed body which will be of a colour proportionate to that of this umbrous body and the illuminated parts of the colour of the window will correspond to the colour of the illuminated body and to the colour of its shades.
The extent to which changes in light and shade are important depends in part on the original colour of the object. On CU787 (TPL636, 1508-1510), for instance, he points out that these changes are least in the case of black:
Which principle shade on the surface of bodies will have less difference from the luminous parts and which will have more?
The shade of black bodies, being primary, will have less difference from its principle lights than in the surface of any other colour.
On CU739 (TPL699, 1508-1510), he notes that these changes are greatest in the case of white:
What colours produce more variety between lights and shades?
Among colours there will be a greater difference between their shades and their lights, which are more similar to whiteness because white has a brighter illumination and darker shade than any other colour, even though neither white nor black are colours.
He compares the effects of light and shade on white, black, green, azure and grey on CU783 (TPL692, 1508-1510):
Where and in what colour shadows lose the natural colour of the umbrous body more?
White, which sees neither incident light, nor any kind of reflected light is that which first loses its proper natural colour entirely in its shadow, if it can be said of white that it is a colour. But black augments its colour in the shadows and loses it to the extent that the illuminated part is seen by light of a greater power.
Both green and azure augment their colour in median shades. And red and yellow acquire colour in their illuminated parts and white does the same and mixed colours participate in the nature of colours which compose such a mixture, that is, black mixed with white makes grey (berettino), which is not beautiful in the final shades as is simple black and it is not beautiful in its lights, as is simple white, but its supreme beauty is between light and shade.
6.5 Light and Beauty
As early as 1492 he is aware that light also augments the beauty of a given colour and hence, on A112r (BN 20-38 33r, CU188, TPL210, 1492) he notes;
How the beauty of a colour must be in its light.
If we see that the quality of colours is understood through light, it can be reckoned that where there is more light there one sees the true quality of the illuminated colour more. And where there is more darkness, the colour tinges itself in the colour of these shadows. Hence, [o] painter, remind yourself to show the truth of colours in the illuminated parts.
He reformulates this idea on CU187 (TPL207, 1505-1510):
How every colour which does not lustre is more beautiful in its luminous parts than in its umbrous parts.
Every colour is more beautiful in its illuminated part than in its shaded part. And this arises because light vivifies and gives true information of the quality of colours and shade weakens and darkens the same beauty and impedes the information of this colour. And if it is objected that black is more beautiful in the shadows than in the lights, it is replied that black is not a colour, nor is white.
On CU189 (TPL242c, 1505-1510), he restates this connection between light and beauty:
The colour which finds itself between the umbrous and the illuminated part of umbrous bodies is of lesser beauty than that which is fully illuminated. Hence the primary beauty of colours is in the principal lights.
He states this idea more forcefully on CU762 (TPL768, 1508-1510):
What part of umbrous bodies will show their colours with a more excellent beauty?
The excellent beauty of a given colour, which does not have lustre in itself, is always in the excellent brightness of the most illuminated part of these umbrous bodies.
In the period 1508-1510 he also explores which colours compliment one another as on CU182 (TPL253):
The colours which belong together are green with red, or purple and violent and yellow and azure.
In the late period he returns once more to the connection between light intensity and beauty in a longer passage on E18r (1513-1514) which opens under the heading:
Colours positioned in the shadows participate that much more or less in their natural beauty to the extent that they are in lesser or greater darkness.
But if the colours are situated in a luminous space, then these will show themselves of that much more beauty to the extent that the light is of greater splendour.
He now introduces the objection of an:
The variety of the colours of shadows are as many as the variety of the colours that these shaded objects have.
This he counters with a:
Colours positioned in the shadows will show themselves of that much less variety to the extent that the shadows which are situated there are darker. And a testimony of this is when from a piazza we look inside the doors of dark temples where paintings covered with various colours appear entirely covered with shadows.
Hence at a long distance all the shadows of the various colours appear of a same darkness.
Among bodies covered with light and shade the illuminated part shows its true colour.
6.6 Darkness and Colour
If greater light shows the truth of colours, greater darkness removes it. Alberti had expressed this corollary succinctly in his On Painting: "As shadow deepens the colours empty out and as the light increases the colours become more open and clear.11 Leonardo broaches this problem in passing in his "prophecies" on CA370ra (1497-1500):
Of the nights which do not know any colour.
You will see so much that the difference between colours is not recognized, on the contrary, they will all be of a black quality.
He again mentions the effects of darkness on colour on CU194 (TPL201, 1505-1510):
Whether various colours can appear of a uniform darkness through a same shadow?
It is possible that all the varieties of colour of a given shadow appear transmuted in the colour of that shadow.
This is manifested in the shadows of cloudy nights in which no shape or colour of a body is recognized. And since darkness is nothing more than the privation of incident light, reflection, through which all the shapes and colours of bodies are understood, it is necessary that when the cause of light has been removed entirely, the effect and recognition of the colours and the shapes of the aforesaid objects is lacking.
On CU696 (TPL715, 1508-1510) he pursues the question:
What is that body which with the same colour and distance from the eye has its lights varying less from its shadows?
That body will show less difference between its shades and lights which will be in air of greater darkness and conversely in air of greater brightness, as is shown by the things placed in the shadows which cannot be recognized and the things which are placed opposite the brightness of the sun, that the shadows appear tenebrous with respect to the parts percussed by the solar rays.
He reformulates this idea on CU740 (TPL713b, 1508-1510) in terms of black surfaces:
What surface makes less difference between bright and dark?
The black surface is again that which will participate more of this blackness, [and] has less difference between its umbrous and luminous parts than any other part, because the illuminated part shows itself to be black and the shaded [part] cannot be other than black, but with little variety it acquires some more darkness than the black illuminated part.
He mentions the problem once more on BM169r (c.1510): "Darkness (tenebre) tinges everything with its colour and the more a thing departs from this darkness, the more it is rendered of its true and natural colour." This idea he restates as a general rule on E30v (CU734, TPL592, 1513-1514):
Quality of shades.
Among equal diminutions of light such will be the proportion from darkness to darkness of this generated shadow as there is from darkness to darkness of the colours where such shades are conjoined.
Elsewhere in the same treatise, on E17v (1513-1514) he reformulates this in terms of two propositions:
5th All colours positioned in umbrous places appear to be of equal darkness among one another.
6th But all colours positioned in luminous places never varyfrom their essence.
6.7 Colour Conclusions
At the outset Leonardo probably intended to write an independent treatise on colour. By the period 1508-1510 he intended to annex this treatise on colour to his work on the rainbow at the end of his book on painting, as is clear from a note on W19076r (K/P167r):
Do the rainbow in the last book on painting, but first do the book on the colours originating from the mixture of other colours such that you can, through these colours of painters, produce the generation of colours of the rainbow.
This explains the close links between his notes on colours and discussions of the rainbow (see below pp. ), which links, in turn, confirm a shift in his thinking. By 1510 theoretical questions concerning the substance of colour are no longer of interest to him. For all practical purposes colour is now a phenomenon of varying light and shade. This is why most of his notes on colour emerge as two chapters of his Books on Light and Shade (see below pp. ).
Leonardo defines darkness as a privation of light, sometimes strengthening this with adjectives such as "entire" (CU665, TPL810, 1505-1510). In the extant notes he repeats this basic definition at least ten times (see Chart 7). On most occasions he treats darkness as an absolute category and carefully distinguishes between shadow and darkness, as on G8r (c.1510-1515): "The shadows of plants are never black because where the air penetrates there cannot be darkness." On rare occasions, as on CA371rb (1510-1515), he suggests that there may also be gradations of darkness: "The percussion of derived shade in darkness is similar to the darkness of this derived shade, that is, the variety of its darkness."
Chart 7: Ten passages in which Leonardo defines darkness as a privation of light.
We have examined Leonardo's analogies between light and sight in order to explain the close parallels between his physics of light and shade and studies of vision. We have also outlined his definitions and categories of light, shade, lustre, colour and darkness were outlined. In the following chapter we shall show how he builds on these basic concepts in drafting his seven "books" on light and shade.
Last Update: July 2, 1999