_The Practice of Painting._
_It is hardly necessary to offer any excuses for the division
carried out in the arrangement of the text into practical
suggestions and theoretical enquiries. It was evidently intended by
Leonardo himself as we conclude from incidental remarks in the MSS.
(for instance No_ 110_). The fact that this arrangement was never
carried out either in the old MS. copies or in any edition since, is
easily accounted for by the general disorder which results from the
provisional distribution of the various chapters in the old copies.
We have every reason to believe that the earliest copyists, in
distributing the materials collected by them, did not in the least
consider the order in which the original MS.lay before them._
_It is evident that almost all the chapters which refer to the
calling and life of the painter--and which are here brought together
in the first section (Nos._ 482-508_)--may be referred to two
distinct periods in Leonardo's life; most of them can be dated as
belonging to the year_ 1492 _or to_ 1515. _At about this later time
Leonardo may have formed the project of completing his Libro della
Pittura, after an interval of some years, as it would seem, during
which his interest in the subject had fallen somewhat into the
background._
_In the second section, which treats first of the artist's studio,
the construction of a suitable window forms the object of careful
investigations; the special importance attached to this by Leonardo
is sufficiently obvious. His theory of the incidence of light which
was fully discussed in a former part of this work, was to him by no
means of mere abstract value, but, being deduced, as he says, from
experience (or experiment) was required to prove its utility in
practice. Connected with this we find suggestions for the choice of
a light with practical hints as to sketching a picture and some
other precepts of a practical character which must come under
consideration in the course of completing the painting. In all this
I have followed the same principle of arrangement in the text as was
carried out in the Theory of Painting, thus the suggestions for the
Perspective of a picture, (Nos._ 536-569_), are followed by the
theory of light and shade for the practical method of optics (Nos._
548--566_) and this by the practical precepts or the treatment of
aerial perspective (_567--570_)._
_In the passage on Portrait and Figure Painting the principles of
painting as applied to a bust and head are separated and placed
first, since the advice to figure painters must have some connection
with the principles of the treatment of composition by which they
are followed._
_But this arrangement of the text made it seem advisable not to pick
out the practical precepts as to the representation of trees and
landscape from the close connection in which they were originally
placed--unlike the rest of the practical precepts--with the theory
of this branch of the subject. They must therefore be sought under
the section entitled Botany for Painters._
_As a supplement to the_ Libro di Pittura _I have here added those
texts which treat of the Painter's materials,--as chalk, drawing
paper, colours and their preparation, of the management of oils and
varnishes; in the appendix are some notes on chemical substances.
Possibly some of these, if not all, may have stood in connection
with the preparation of colours. It is in the very nature of things
that Leonardo's incidental indications as to colours and the like
should be now-a-days extremely obscure and could only be explained
by professional experts--by them even in but few instances. It might
therefore have seemed advisable to reproduce exactly the original
text without offering any translation. The rendering here given is
merely an attempt to suggest what Leonardo's meaning may have been._
_LOMAZZO tells us in his_ Trattato dell'arte della Pittura, Scultura
ed Architettura (Milano 1584, libro II, Cap. XIV): "Va discorrendo
ed argomentando Leonardo Vinci in un suo libro letto da me (?)
questi anni passati, ch'egli scrisse di mano stanca ai prieghi di
LUDOVICO SFORZA duca di Milano, in determinazione di questa
questione, se e piu nobile la pittura o la scultura; dicendo che
quanto piu un'arte porta seco fatica di corpo, e sudore, tanto piu e
vile, e men pregiata". _But the existence of any book specially
written for Lodovico il Moro on the superiority of Painting over
sculpture is perhaps mythical. The various passages in praise of
Painting as compared not merely with Sculpture but with Poetry, are
scattered among MSS. of very different dates._
_Besides, the way, in which the subject is discussed appears not to
support the supposition, that these texts were prepared at a special
request of the Duke._