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VOLUME I: SECTION V. THEORY OF COLOURS
Leonardo's theory of colours is even more intimately connected with
his principles of light and shade than his Perspective of
Disappearance and is in fact merely an appendix or supplement to
those principles, as we gather from the titles to sections_ 264,
267_, and _276_, while others again_ (_Nos._ 281, 282_) are headed_
Prospettiva.
A very few of these chapters are to be found in the oldest copies
and editions of the Treatise on Painting, and although the material
they afford is but meager and the connection between them but
slight, we must still attribute to them a special theoretical value
as well as practical utility--all the more so because our knowledge
of the theory and use of colours at the time of the Renaissance is
still extremely limited._
The reciprocal effects of colours on objects placed opposite each other (263-272) 263.
OF PAINTING.
The hue of an illuminated object is affected by that of the luminous
body.
264.
OF SHADOW.
The surface of any opaque body is affected by the colour of
surrounding objects.
265.
A shadow is always affected by the colour of the surface on which it is cast.
266.
An image produced in a mirror is affected by the colour of the mirror.
267.
OF LIGHT AND SHADE.
Every portion of the surface of a body is varied [in hue] by the
[reflected] colour of the object that may be opposite to it.
EXAMPLE.
If you place a spherical body between various objects that is to say
with [direct] sunlight on one side of it, and on the other a wall
illuminated by the sun, which wall may be green or of any other
colour, while the surface on which it is placed may be red, and the
two lateral sides are in shadow, you will see that the natural
colour of that body will assume something of the hue reflected from
those objects. The strongest will be [given by] the luminous body;
the second by the illuminated wall, the third by the shadows. There
will still be a portion which will take a tint from the colour of
the edges.
268.
The surface of every opaque body is affected by the colour of the
objects surrounding it. But this effect will be strong or weak in
proportion as those objects are more or less remote and more or less
strongly [coloured].
269.
OF PAINTING.
The surface of every opaque body assumes the hues reflected from
surrounding objects.
The surface of an opaque body assumes the hues of surrounding
objects more strongly in proportion as the rays that form the images
of those objects strike the surface at more equal angles.
And the surface of an opaque body assumes a stronger hue from the
surrounding objects in proportion as that surface is whiter and the
colour of the object brighter or more highly illuminated.
270.
OF THE RAYS WHICH CONVEY THROUGH THE AIR THE IMAGES OF OBJECTS.
All the minutest parts of the image intersect each other without
interfering with each other. To prove this let _r_ be one of the
sides of the hole, opposite to which let _s_ be the eye which sees
the lower end _o_ of the line _n o_. The other extremity cannot
transmit its image to the eye _s_ as it has to strike the end _r_
and it is the same with regard to _m_ at the middle of the line. The
case is the same with the upper extremity _n_ and the eye _u_. And
if the end _n_ is red the eye _u_ on that side of the holes will not
see the green colour of _o_, but only the red of _n_ according to
the 7th of this where it is said: Every form projects images from
itself by the shortest line, which necessarily is a straight line,
&c.
[Footnote: 13. This probably refers to the diagram given under No. 66.]
271.
OF PAINTING.
The surface of a body assumes in some degree the hue of those around
it. The colours of illuminated objects are reflected from the
surfaces of one to the other in various spots, according to the
various positions of those objects. Let _o_ be a blue object in full
light, facing all by itself the space _b c_ on the white sphere _a b
e d e f_, and it will give it a blue tinge, _m_ is a yellow body
reflected onto the space _a b_ at the same time as _o_ the blue
body, and they give it a green colour (by the 2nd [proposition] of
this which shows that blue and yellow make a beautiful green &c.)
And the rest will be set forth in the Book on Painting. In that Book
it will be shown, that, by transmitting the images of objects and
the colours of bodies illuminated by sunlight through a small round
perforation and into a dark chamber onto a plane surface, which
itself is quite white, &c.
But every thing will be upside down.
Combination of different colours in cast shadows (272) That which casts the shadow does not face it, because the shadows
are produced by the light which causes and surrounds the shadows.
The shadow caused by the light _e_, which is yellow, has a blue
tinge, because the shadow of the body _a_ is cast upon the pavement
at _b_, where the blue light falls; and the shadow produced by the
light _d_, which is blue, will be yellow at _c_, because the yellow
light falls there and the surrounding background to these shadows _b
c_ will, besides its natural colour, assume a hue compounded of
yellow and blue, because it is lighted by the yellow light and by
the blue light both at once.
Shadows of various colours, as affected by the lights falling on
them. That light which causes the shadow does not face it.
[Footnote: In the original diagram we find in the circle _e_
"_giallo_" (yellow) and the cirle _d_ "_azurro"_ (blue) and also
under the circle of shadow to the left "_giallo_" is written and
under that to the right "_azurro_".
In the second diagram where four circles are placed in a row we find
written, beginning at the left hand, "_giallo_" (yellow), "_azurro_"
(blue), "_verde_" (green), "_rosso_" (red).]
The effect of colours in the camera obscura (273-274) 273.
The edges of a colour(ed object) transmitted through a small hole
are more conspicuous than the central portions.
The edges of the images, of whatever colour, which are transmitted
through a small aperture into a dark chamber will always be stronger
than the middle portions.
274.
OF THE INTERSECTIONS OF THE IMAGES IN THE PUPIL OF THE EYE.
The intersections of the images as they enter the pupil do not
mingle in confusion in the space where that intersection unites
them; as is evident, since, if the rays of the sun pass through two
panes of glass in close contact, of which one is blue and the other
yellow, the rays, in penetrating them, do not become blue or yellow
but a beautiful green. And the same thing would happen in the eye,
if the images which were yellow or green should mingle where they
[meet and] intersect as they enter the pupil. As this does not
happen such a mingling does not exist.
OF THE NATURE OF THE RAYS COMPOSED OF THE IMAGES OF OBJECTS, AND OF
THEIR INTERSECTIONS.
The directness of the rays which transmit the forms and colours of
the bodies whence they proceed does not tinge the air nor can they
affect each other by contact where they intersect. They affect only
the spot where they vanish and cease to exist, because that spot
faces and is faced by the original source of these rays, and no
other object, which surrounds that original source can be seen by
the eye where these rays are cut off and destroyed, leaving there
the spoil they have conveyed to it. And this is proved by the 4th
[proposition], on the colour of bodies, which says: The surface of
every opaque body is affected by the colour of surrounding objects;
hence we may conclude that the spot which, by means of the rays
which convey the image, faces--and is faced by the cause of the
image, assumes the colour of that object.
On the colours of derived shadows (275-276) 275.
ANY SHADOW CAST BY AN OPAQUE BODY SMALLER THAN THE LIGHT CAUSING THE
SHADOW WILL THROW A DERIVED SHADOW WHICH IS TINGED BY THE COLOUR OF
THE LIGHT.
Let _n_ be the source of the shadow _e f_; it will assume its hue.
Let _o_ be the source of _h e_ which will in the same way be tinged
by its hue and so also the colour of _v h_ will be affected by _p_
which causes it; and the shadow of the triangle _z k y_ will be
affected by the colour of _q_, because it is produced by it. [7] In
proportion as _c d_ goes into _a d_, will _n r s_ be darker than
_m_; and the rest of the space will be shadowless [11]. _f g_ is
the highest light, because here the whole light of the window _a d_
falls; and thus on the opaque body _m e_ is in equally high light;
_z k y_ is a triangle which includes the deepest shadow, because the
light _a d_ cannot reach any part of it. _x h_ is the 2nd grade of
shadow, because it receives only 1/3 of the light from the window,
that is _c d_. The third grade of shadow is _h e_, where two thirds
of the light from the window is visible. The last grade of shadow is
_b d e f_, because the highest grade of light from the window falls
at _f_.
[Footnote: The diagram Pl. III, No. 1 belongs to this chapter as
well as the text given in No. 148. Lines 7-11 (compare lines 8-12 of
No. 148) which are written within the diagram, evidently apply to
both sections and have therefore been inserted in both.]
276.
OF THE COLOURS OF SIMPLE DERIVED SHADOWS.
The colour of derived shadows is always affected by that of the body
towards which they are cast. To prove this: let an opaque body be
placed between the plane _s c t d_ and the blue light _d e_ and the
red light _a b_, then I say that _d e_, the blue light, will fall on
the whole surface _s c t d_ excepting at _o p_ which is covered by
the shadow of the body _q r_, as is shown by the straight lines _d q
o e r p_. And the same occurs with the light _a b_ which falls on
the whole surface _s c t d_ excepting at the spot obscured by the
shadow _q r_; as is shown by the lines _d q o_, and _e r p_. Hence
we may conclude that the shadow _n m_ is exposed to the blue light
_d e_; but, as the red light _a b_ cannot fall there, _n m_ will
appear as a blue shadow on a red background tinted with blue,
because on the surface _s c t d_ both lights can fall. But in the
shadows only one single light falls; for this reason these shadows
are of medium depth, since, if no light whatever mingled with the
shadow, it would be of the first degree of darkness &c. But in the
shadow at _o p_ the blue light does not fall, because the body _q r_
interposes and intercepts it there. Only the red light _a b_ falls
there and tinges the shadow of a red hue and so a ruddy shadow
appears on the background of mingled red and blue.
The shadow of _q r_ at _o p_ is red, being caused by the blue light
_d e_; and the shadow of _q r_ at _o' p'_ is blue being caused by
the red light _a b_. Hence we say that the blue light in this
instance causes a red derived shadow from the opaque body _q' r'_,
while the red light causes the same body to cast a blue derived
shadow; but the primary shadow [on the dark side of the body itself]
is not of either of those hues, but a mixture of red and blue.
The derived shadows will be equal in depth if they are produced by
lights of equal strength and at an equal distance; this is proved.
[Footnote 53: The text is unfinished in the original.]
[Footnote: In the original diagram Leonardo has written within the
circle _q r corpo obroso_ (body in shadow); at the spot marked _A,
luminoso azzurro_ (blue luminous body); at _B, luminoso rosso_ (red
luminous body). At _E_ we read _ombra azzurra_ (blue tinted shadow)
and at _D ombra rossa_ (red tinted shadow).]
On the nature of colours (277-278) 277.
No white or black is transparent.
278.
OF PAINTING.
[Footnote 2: See Footnote 3] Since white is not a colour but the
neutral recipient of every colour [Footnote 3: _il bianco non e
colore ma e inpotentia ricettiva d'ogni colore_ (white is not a
colour, but the neutral recipient of every colour). LEON BATT.
ALBERTI "_Della pittura_" libro I, asserts on the contrary: "_Il
bianco e'l nero non sono veri colori, ma sono alteratione delli
altri colori_" (ed. JANITSCHEK, p. 67; Vienna 1877).], when it is
seen in the open air and high up, all its shadows are bluish; and
this is caused, according to the 4th [prop.], which says: the
surface of every opaque body assumes the hue of the surrounding
objects. Now this white [body] being deprived of the light of the
sun by the interposition of some body between the sun and itself,
all that portion of it which is exposed to the sun and atmosphere
assumes the colour of the sun and atmosphere; the side on which the
sun does not fall remains in shadow and assumes the hue of the
atmosphere. And if this white object did not reflect the green of
the fields all the way to the horizon nor get the brightness of the
horizon itself, it would certainly appear simply of the same hue as
the atmosphere.
On gradations in the depth of colours (279-280) 279.
Since black, when painted next to white, looks no blacker than when
next to black; and white when next to black looks no whiter than
white, as is seen by the images transmitted through a small hole or
by the edges of any opaque screen ...
280.
OF COLOURS.
Of several colours, all equally white, that will look whitest which
is against the darkest background. And black will look intensest
against the whitest background.
And red will look most vivid against the yellowest background; and
the same is the case with all colours when surrounded by their
strongest contrasts.
On the reflection of colours (281-283) 281.
PERSPECTIVE.
Every object devoid of colour in itself is more or less tinged by
the colour [of the object] placed opposite. This may be seen by
experience, inasmuch as any object which mirrors another assumes the
colour of the object mirrored in it. And if the surface thus
partially coloured is white the portion which has a red reflection
will appear red, or any other colour, whether bright or dark.
PERSPECTIVE.
Every opaque and colourless body assumes the hue of the colour
reflected on it; as happens with a white wall.
282.
PERSPECTIVE.
That side of an object in light and shade which is towards the light
transmits the images of its details more distinctly and immediately
to the eye than the side which is in shadow.
PERSPECTIVE.
The solar rays reflected on a square mirror will be thrown back to
distant objects in a circular form.
PERSPECTIVE.
Any white and opaque surface will be partially coloured by
reflections from surrounding objects.
[Footnote 281. 282: The title line of these chapters is in the
original simply _"pro"_, which may be an abbreviation for either
_Propositione_ or _Prospettiva_--taking Prospettiva of course in its
widest sense, as we often find it used in Leonardo's writings. The
title _"pro"_ has here been understood to mean _Prospettiva_, in
accordance with the suggestion afforded by page 10b of this same
MS., where the first section is headed _Prospettiva_ in full (see
No. 94), while the four following sections are headed merely _"pro"_
(see No. 85).]
283.
WHAT PORTION OF A COLOURED SURFACE OUGHT IN REASON TO BE THE MOST
INTENSE.
If _a_ is the light, and _b_ illuminated by it in a direct line,
_c_, on which the light cannot fall, is lighted only by reflection
from _b_ which, let us say, is red. Hence the light reflected from
it, will be affected by the hue of the surface causing it and will
tinge the surface _c_ with red. And if _c_ is also red you will see
it much more intense than _b_; and if it were yellow you would see
there a colour between yellow and red.
On the use of dark and light colours in painting (284-286) 284.
WHY BEAUTIFUL COLOURS MUST BE IN THE [HIGHEST] LIGHT.
Since we see that the quality of colour is known [only] by means of
light, it is to be supposed that where there is most light the true
character of a colour in light will be best seen; and where there is
most shadow the colour will be affected by the tone of that. Hence,
O Painter! remember to show the true quality of colours in bright
lights.
285.
An object represented in white and black will display stronger
relief than in any other way; hence I would remind you O Painter! to
dress your figures in the lightest colours you can, since, if you
put them in dark colours, they will be in too slight relief and
inconspicuous from a distance. And the reason is that the shadows of
all objects are dark. And if you make a dress dark there is little
variety in the lights and shadows, while in light colours there are
many grades.
286.
OF PAINTING.
Colours seen in shadow will display more or less of their natural
brilliancy in proportion as they are in fainter or deeper shadow.
But if these same colours are situated in a well-lighted place, they
will appear brighter in proportion as the light is more brilliant.
THE ADVERSARY.
The variety of colours in shadow must be as great as that of the
colours in the objects in that shadow.
THE ANSWER.
Colours seen in shadow will display less variety in proportion as
the shadows in which they lie are deeper. And evidence of this is to
be had by looking from an open space into the doorways of dark and
shadowy churches, where the pictures which are painted in various
colours all look of uniform darkness.
Hence at a considerable distance all the shadows of different
colours will appear of the same darkness.
It is the light side of an object in light and shade which shows the
true colour.
On the colours of the rainbow (287-288) 287.
Treat of the rainbow in the last book on Painting, but first write
the book on colours produced by the mixture of other colours, so as
to be able to prove by those painters' colours how the colours of
the rainbow are produced.
288.
WHETHER THE COLOURS OF THE RAINBOW ARE PRODUCED BY THE SUN.
The colours of the rainbow are not produced by the sun, for they
occur in many ways without the sunshine; as may be seen by holding a
glass of water up to the eye; when, in the glass--where there are
those minute bubbles always seen in coarse glass--each bubble, even
though the sun does not fall on it, will produce on one side all the
colours of the rainbow; as you may see by placing the glass between
the day light and your eye in such a way as that it is close to the
eye, while on one side the glass admits the [diffused] light of the
atmosphere, and on the other side the shadow of the wall on one side
of the window; either left or right, it matters not which. Then, by
turning the glass round you will see these colours all round the
bubbles in the glass &c. And the rest shall be said in its place.
THAT THE EYE HAS NO PART IN PRODUCING THE COLOURS OF THE RAINBOW.
In the experiment just described, the eye would seem to have some
share in the colours of the rainbow, since these bubbles in the
glass do not display the colours except through the medium of the
eye. But, if you place the glass full of water on the window sill,
in such a position as that the outer side is exposed to the sun's
rays, you will see the same colours produced in the spot of light
thrown through the glass and upon the floor, in a dark place, below
the window; and as the eye is not here concerned in it, we may
evidently, and with certainty pronounce that the eye has no share in
producing them.
OF THE COLOURS IN THE FEATHERS OF CERTAIN BIRDS.
There are many birds in various regions of the world on whose
feathers we see the most splendid colours produced as they move, as
we see in our own country in the feathers of peacocks or on the
necks of ducks or pigeons, &c.
Again, on the surface of antique glass found underground and on the
roots of turnips kept for some time at the bottom of wells or other
stagnant waters [we see] that each root displays colours similar to
those of the real rainbow. They may also be seen when oil has been
placed on the top of water and in the solar rays reflected from the
surface of a diamond or beryl; again, through the angular facet of a
beryl every dark object against a background of the atmosphere or
any thing else equally pale-coloured is surrounded by these rainbow
colours between the atmosphere and the dark body; and in many other
circumstances which I will not mention, as these suffice for my
purpose. _