The Notebooks of Leonardo Da Vinci (18 page)

On the colours of derived shadows (275. 276).

275.

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.

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.

[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 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.

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.

Every opaque and colourless body assumes the hue of the colour
reflected on it; as happens with a white wall.

282.

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.

The solar rays reflected on a square mirror will be thrown back to
distant objects in a circular form.

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.

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.

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.

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 variety of colours in shadow must be as great as that of the
colours in the objects in that shadow.

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.

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.

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.

'Prospettiva de' colri' (Perspective of Colour)

and

'Prospettiva aerea' (Aerial Perspective).

Leonardo distinctly separates these branches of his subject, as may
be seen in the beginning of No.
295.
Attempts have been made to
cast doubts on the results which Leonardo arrived at by experiment
on the perspective of colour, but not with justice, as may be seen
from the original text of section
294.