That part of a tree will show the fewest spaces, behind which a large number of trees are standing between the tree and the air [sky]; thus in the tree _a_ the spaces are not concealed nor in _b_, as there is no tree behind. But in _c_ only half shows the spaces filled up by the tree _d_, and part of the tree _d_ is filled up by the tree _e_ and a little farther on all the spaces in the mass of the trees are lost, and only that at the side remains. 451. OF TREES. What outlines are seen in trees at a distance against the sky which serves as their background? The outlines of the ramification of trees, where they lie against the illuminated sky, display a form which more nearly approaches the spherical on proportion as they are remote, and the nearer they are the less they appear in this spherical form; as in the first tree _a_ which, being near to the eye, displays the true form of its ramification; but this shows less in _b_ and is altogether lost in _c_, where not merely the branches of the tree cannot be seen but the whole tree is distinguished with difficulty. Every object in shadow, of whatever form it may be, at a great distance appears to be spherical. And this occurs because, if it is a square body, at a very short distance it loses its angles, and a little farther off it loses still more of its smaller sides which remain. And thus before the whole is lost [to sight] the parts are lost, being smaller than the whole; as a man, who in such a distant position loses his legs, arms and head before [the mass of] his body, then the outlines of length are lost before those of breadth, and where they have become equal it would be a square if the angles remained; but as they are lost it is round. [Footnote: The sketch No. 4, Pl. XXVIII, belongs to this passage.] The cast shadow of trees (452. 453). 452. The image of the shadow of any object of uniform breadth can never be [exactly] the same as that of the body which casts it. [Footnote: See Pl. XXVIII, No. 5.] Light and shade on groups of trees (453-457). 453. All trees seen against the sun are dark towards the middle and this shadow will be of the shape of the tree when apart from others. The shadows cast by trees on which the sun shines are as dark as those of the middle of the tree. The shadow cast by a tree is never less than the mass of the tree but becomes taller in proportion as the spot on which it falls, slopes towards the centre of the world. The shadow will be densest in the middle of the tree when the tree has the fewest branches. [Footnote: The three diagrams which accompany this text are placed, in the original, before lines 7-11. At the spots marked _B_ Leonardo wrote _Albero_ (tree). At _A_ is the word _Sole_ (sun), at _C Monte_ (mountain) at _D piano_ (plain) and at _E cima_ (summit).] Every branch participates of the central shadow of every other branch and consequently [of that] of the whole tree.