The Notebooks of Leonardo Da Vinci (26 page)

416.

The ramifications of any tree, such as the elm, are wide and slender
after the manner of a hand with spread fingers, foreshortened. And
these are seen in the distribution [thus]: the lower portions are
seen from above; and those that are above are seen from below; and
those in the middle, some from below and some from above. The upper
part is the extreme [top] of this ramification and the middle
portion is more foreshortened than any other of those which are
turned with their tips towards you. And of those parts of the middle
of the height of the tree, the longest will be towards the top of
the tree and will produce a ramification like the foliage of the
common willow, which grows on the banks of rivers.

Other ramifications are spherical, as those of such trees as put
forth their shoots and leaves in the order of the sixth being placed
above the first. Others are thin and light like the willow and
others.

417.

You will see in the lower branches of the elder, which puts forth
leaves two and two placed crosswise [at right angles] one above
another, that if the stem rises straight up towards the sky this
order never fails; and its largest leaves are on the thickest part
of the stem and the smallest on the slenderest part, that is towards
the top. But, to return to the lower branches, I say that the leaves
on these are placed on them crosswise like [those on] the upper
branches; and as, by the law of all leaves, they are compelled to
turn their upper surface towards the sky to catch the dew at night,
it is necessary that those so placed should twist round and no
longer form a cross.

[Footnote: See Pl. XXVII, No. 5.]

418.

A leaf always turns its upper side towards the sky so that it may
the better receive, on all its surface, the dew which drops gently
from the atmosphere. And these leaves are so distributed on the
plant as that one shall cover the other as little as possible, but
shall lie alternately one above another as may be seen in the ivy
which covers the walls. And this alternation serves two ends; that
is, to leave intervals by which the air and sun may penetrate
between them. The 2nd reason is that the drops which fall from the
first leaf may fall onto the fourth or—in other trees—onto the
sixth.

419.

Every shoot and every fruit is produced above the insertion [in the
axil] of its leaf which serves it as a mother, giving it water from
the rain and moisture from the dew which falls at night from above,
and often it protects them against the too great heat of the rays of
the sun.

420.

That part of the body will be most illuminated which is hit by the
luminous ray coming between right angles.

[Footnote: See Pl. XXVIII, No. 1.]

421.

Young plants have more transparent leaves and a more lustrous bark
than old ones; and particularly the walnut is lighter coloured in
May than in September.

422.

The accidents of colour in the foliage of trees are 4. That is:
shadow, light, lustre [reflected light] and transparency.

These accidents of colour in the foliage of trees become confused at
a great distance and that which has most breadth [whether light or
shade, &c.] will be most conspicuous.

The proportions of light and shade in a leaf (423-426).

423.

Sometimes a leaf has three accidents [of light] that is: shade,
lustre [reflected light] and transparency [transmitted light]. Thus,
if the light were at
n
as regards the leaf
s
, and the eye at
m
, it would see
a
in full light,
b
in shadow and
c
transparent.

424.

A leaf with a concave surface seen from the under side and
up-side-down will sometimes show itself as half in shade, and half
transparent. Thus, if
o p
is the leaf and the light
m
and the
eye
n
, this will see
o
in shadow because the light does not fall
upon it between equal angles, neither on the upper nor the under
side, and
p
is lighted on the upper side and the light is
transmitted to its under side. [Footnote: See Pl. XXVIII, No. 2, the
upper sketch on the page. In the original they are drawn in red
chalk.]

425.

Although those leaves which have a polished surface are to a great
extent of the same colour on the right side and on the reverse, it
may happen that the side which is turned towards the atmosphere will
have something of the colour of the atmosphere; and it will seem to
have more of this colour of the atmosphere in proportion as the eye
is nearer to it and sees it more foreshortened. And, without
exception the shadows show as darker on the upper side than on the
lower, from the contrast offered by the high lights which limit the
shadows.

The under side of the leaf, although its colour may be in itself the
same as that of the upper side, shows a still finer colour—a colour
that is green verging on yellow—and this happens when the leaf is
placed between

426.

the eye and the light which falls upon it from the opposite side.

And its shadows are in the same positions as those were of the
opposite side. Therefore, O Painter! when you do trees close at
hand, remember that if the eye is almost under the tree you will see
its leaves [some] on the upper and [some] on the under side, and the
upper side will be bluer in proportion as they are seen more
foreshortened, and the same leaf sometimes shows part of the right
side and part of the under side, whence you must make it of two
colours.

Of the transparency of leaves (427-429).

427.

The shadows in transparent leaves seen from the under side are the
same shadows as there are on the right side of this leaf, they will
show through to the underside together with lights, but the lustre
[reflected light] can never show through.

428.

When one green has another [green] behind it, the lustre on the
leaves and their transparent [lights] show more strongly than in
those which are [seen] against the brightness of the atmosphere.

And if the sun illuminates the leaves without their coming between
it and the eye and without the eye facing the sun, then the
reflected lights and the transparent lights are very strong.

It is very effective to show some branches which are low down and
dark and so set off the illuminated greens which are at some
distance from the dark greens seen below. That part is darkest which
is nearest to the eye or which is farthest from the luminous
atmosphere.

429.

Never paint leaves transparent to the sun, because they are
confused; and this is because on the transparency of one leaf will
be seen the shadow of another leaf which is above it. This shadow
has a distinct outline and a certain depth of shade and sometimes is
[as much as] half or a third of the leaf which is shaded; and
consequently such an arrangement is very confused and the imitation
of it should be avoided.

The light shines least through a leaf when it falls upon it at an
acute angle.

The gradations of shade and colour in leaves (430-434).

430.

The shadows of plants are never black, for where the atmosphere
penetrates there can never be utter darkness.

431.

If the light comes from
m
and the eye is at
n
the eye will see
the colour of the leaves
a b
all affected by the colour of
m
—that is of the atmosphere; and
b c
will be seen from the under
side as transparent, with a beautiful green colour verging on
yellow.

If
m
is the luminous body lighting up the leaf
s
all the eyes
that see the under side of this leaf will see it of a beautiful
light green, being transparent.

In very many cases the positions of the leaves will be without
shadow [or in full light], and their under side will be transparent
and the right side lustrous [reflecting light].

432.

The willow and other similar trees, which have their boughs lopped
every 3 or 4 years, put forth very straight branches, and their
shadow is about the middle where these boughs spring; and towards
the extreme ends they cast but little shade from having small leaves
and few and slender branches. Hence the boughs which rise towards
the sky will have but little shade and little relief; and the
branches which are at an angle from the horizon, downwards, spring
from the dark part of the shadow and grow thinner by degrees up to
their ends, and these will be in strong relief, being in gradations
of light against a background of shadow.

That tree will have the least shadow which has the fewest branches
and few leaves.

433.

When the leaves are interposed between the light and the eye, then
that which is nearest to the eye will be the darkest, and the most
distant will be the lightest, not being seen against the atmosphere;
and this is seen in the leaves which are away from the centre of the
tree, that is towards the light.

[Footnote: See Pl. XXVIII, No. 2, the lower sketch.]

434.

The lights on such leaves which are darkest, will be most near to
the colour of the atmosphere that is reflected in them. And the
cause of this is that the light on the illuminated portion mingles
with the dark hue to compose a blue colour; and this light is
produced by the blueness of the atmosphere which is reflected in the
smooth surface of these leaves and adds to the blue hue which this
light usually produces when it falls on dark objects.

But leaves of a green verging on yellow when they reflect the
atmosphere do not produce a reflection verging on blue, inasmuch as
every thing which appears in a mirror takes some colour from that
mirror, hence the blue of the atmosphere being reflected in the
yellow of the leaf appears green, because blue and yellow mixed
together make a very fine green colour, therefore the lustre of
light leaves verging on yellow will be greenish yellow.

A classification of trees according to their colours.

435.

The trees in a landscape are of various kinds of green, inasmuch as
some verge towards blackness, as firs, pines, cypresses, laurels,
box and the like. Some tend to yellow such as walnuts, and pears,
vines and verdure. Some are both yellowish and dark as chesnuts,
holm-oak. Some turn red in autumn as the service-tree, pomegranate,
vine, and cherry; and some are whitish as the willow, olive, reeds
and the like. Trees are of various forms …

The proportions of light and shade in trees (436-440).

436.

That part of the trees will be seen to lie in the least dark shadow
which is farthest from the earth.

To prove it let
a p
be the tree,
n b c
the illuminated
hemisphere [the sky], the under portion of the tree faces the earth
p c
, that is on the side
o
, and it faces a small part of the
hemisphere at
c d
. But the highest part of the convexity a faces
the greatest part of the hemisphere, that is
b c
. For this
reason—and because it does not face the darkness of the earth—it
is in fuller light. But if the tree has dense foliage, as the
laurel, arbutus, box or holm oak, it will be different; because,
although
a
does not face the earth, it faces the dark [green] of
the leaves cut up by many shadows, and this darkness is reflected
onto the under sides of the leaves immediately above. Thus these
trees have their darkest shadows nearest to the middle of the tree.

437.

The shadows of verdure are always somewhat blue, and so is every
shadow of every object; and they assume this hue more in proportion
as they are remote from the eye, and less in proportion as they are
nearer. The leaves which reflect the blue of the atmosphere always
present themselves to the eye edgewise.

The illuminated portion, at a great distance, will appear most
nearly of its natural colour where the strongest light falls upon
it.

438.

In trees that are illuminated [both] by the sun and the atmosphere
and that have leaves of a dark colour, one side will be illuminated
by the atmosphere [only] and in consequence of this light will tend
to blueness, while on the other side they will be illuminated by the
atmosphere and the sun; and the side which the eye sees illuminated
by the sun will reflect light.

439.

The trees and plants which are most thickly branched with slender
branches ought to have less dark shadow than those trees and plants
which, having broader leaves, will cast more shadow.

440.

In the position of the eye which sees that portion of a tree
illuminated which turns towards the light, one tree will never be
seen to be illuminated equally with the other. To prove this, let
the eye be
c
which sees the two trees
b d
which are illuminated
by the sun
a
; I say that this eye
c
will not see the light in
the same proportion to the shade, in one tree as in the other.
Because, the tree which is nearest to the sun will display so much
the stronger shadow than the more distant one, in proportion as one
tree is nearer to the rays of the sun that converge to the eye than
the other; &c.