The first thing in painting is that the objects it represents should
appear in relief, and that the grounds surrounding them at different
distances shall appear within the vertical plane of the foreground
of the picture by means of the 3 branches of Perspective, which are:
the diminution in the distinctness of the forms of the objects, the
diminution in their magnitude; and the diminution in their colour.
And of these 3 classes of Perspective the first results from [the
structure of] the eye, while the other two are caused by the
atmosphere which intervenes between the eye and the objects seen by
it. The second essential in painting is appropriate action and a due
variety in the figures, so that the men may not all look like
brothers, &c.
[Footnote: This and the two foregoing chapters must have been
written in 1513 to 1516. They undoubtedly indicate the scheme which
Leonardo wished to carry out in arranging his researches on
Perspective as applied to Painting. This is important because it is
an evidence against the supposition of H. LUDWIG and others, that
Leonardo had collected his principles of Perspective in one book so
early as before 1500; a Book which, according to the hypothesis,
must have been lost at a very early period, or destroyed possibly,
by the French (!) in 1500 (see H. LUDWIG. L. da Vinci: _Das Buch van
der Malerei_. Vienna 1882 III, 7 and 8).]
The use of the book on Painting.
18.
These rules are of use only in correcting the figures; since every
man makes some mistakes in his first compositions and he who knows
them not, cannot amend them. But you, knowing your errors, will
correct your works and where you find mistakes amend them, and
remember never to fall into them again. But if you try to apply
these rules in composition you will never make an end, and will
produce confusion in your works.
These rules will enable you to have a free and sound judgment; since
good judgment is born of clear understanding, and a clear
understanding comes of reasons derived from sound rules, and sound
rules are the issue of sound experience--the common mother of all
the sciences and arts. Hence, bearing in mind the precepts of my
rules, you will be able, merely by your amended judgment, to
criticise and recognise every thing that is out of proportion in a
work, whether in the perspective or in the figures or any thing
else.
Necessity of theoretical knowledge (19. 20).
19.