The Nots, vol 1 | Page 9

preeminently (tends to) elevate
the mind of the investigator. Perspective, therefore, must be preferred
to all the discourses and systems of human learning. In this branch [of
science] the beam of light is explained on those methods of
demonstration which form the glory not so much of Mathematics as of
Physics and are graced with the flowers of both [Footnote: 5. Such of
Leonardo's notes on Optics or on Perspective as bear exclusively on
Mathematics or Physics could not be included in the arrangement of the
libro di pittura which is here presented to the reader. They are however
but few.]. But its axioms being laid down at great length, I shall abridge
them to a conclusive brevity, arranging them on the method both of
their natural order and of mathematical demonstration; sometimes by
deduction of the effects from the causes, and sometimes arguing the
causes from the effects; adding also to my own conclusions some
which, though not included in them, may nevertheless be inferred from
them. Thus, if the Lord--who is the light of all things--vouchsafe to
enlighten me, I will treat of Light; wherefore I will divide the present
work into 3 Parts [Footnote: 10. In the middle ages--for instance, by
ROGER BACON, by VITELLONE, with whose works Leonardo was
certainly familiar, and by all the writers of the Renaissance Perspective
and Optics were not regarded as distinct sciences. Perspective, indeed,
is in its widest application the science of seeing. Although to Leonardo
the two sciences were clearly separate, it is not so as to their names;
thus we find axioms in Optics under the heading Perspective.
According to this arrangement of the materials for the theoretical
portion of the libro di pittura propositions in Perspective and in Optics

stand side by side or occur alternately. Although this particular chapter
deals only with Optics, it is not improbable that the words _partirò la
presente opera in 3 parti_ may refer to the same division into three
sections which is spoken of in chapters 14 to 17.].
The plan of the book on Painting (14--17).
14.
ON THE THREE BRANCHES OF PERSPECTIVE.
There are three branches of perspective; the first deals with the reasons
of the (apparent) diminution of objects as they recede from the eye, and
is known as Diminishing Perspective.--The second contains the way in
which colours vary as they recede from the eye. The third and last is
concerned with the explanation of how the objects [in a picture] ought
to be less finished in proportion as they are remote (and the names are
as follows):
Linear Perspective. The Perspective of Colour. The Perspective of
Disappearance.
[Footnote: 13. From the character of the handwriting I infer that this
passage was written before the year 1490.].
15.
ON PAINTING AND PERSPECTIVE.
The divisions of Perspective are 3, as used in drawing; of these, the
first includes the diminution in size of opaque objects; the second treats
of the diminution and loss of outline in such opaque objects; the third,
of the diminution and loss of colour at long distances.
[Footnote: The division is here the same as in the previous chapter No.
14, and this is worthy of note when we connect it with the fact that a
space of about 20 years must have intervened between the writing of
the two passages.]
16.
THE DISCOURSE ON PAINTING.
Perspective, as bearing on drawing, is divided into three principal
sections; of which the first treats of the diminution in the size of bodies
at different distances. The second part is that which treats of the
diminution in colour in these objects. The third [deals with] the
diminished distinctness of the forms and outlines displayed by the
objects at various distances.
17.

ON THE SECTIONS OF [THE BOOK ON] PAINTING.
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