where it stood in the original document. Thus, too, by following the
sequence of the numbers in the Bibliographical index, the reader may
reconstruct the original order of the Manuscripts and recompose the
various texts to be found on the original sheets--so much of it,
that is to say, as by its subject-matter came within the scope of
this work. It may, however, be here observed that Leonardo s
Manuscripts contain, besides the passages here printed, a great
number of notes and dissertations on Mechanics, Physics, and some
other subjects, many of which could only be satisfactorily dealt
with by specialists. I have given as complete a review of these
writings as seemed necessary in the Bibliographical notes.

In 1651, Raphael Trichet Dufresne, of Paris, published a selection
from Leonardo's writings on painting, and this treatise became so
popular that it has since been reprinted about two-and-twenty times,
and in six different languages. But none of these editions were
derived from the original texts, which were supposed to have been
lost, but from early copies, in which Leonardo's text had been more
or less mutilated, and which were all fragmentary. The oldest and on
the whole the best copy of Leonardo's essays and precepts on
Painting is in the Vatican Library; this has been twice printed,
first by Manzi, in 1817, and secondly by Ludwig, in 1882. Still,
this ancient copy, and the published editions of it, contain much
for which it would be rash to hold Leonardo responsible, and some
portions--such as the very important rules for the proportions of
the human figure--are wholly wanting; on the other hand they contain
passages which, if they are genuine, cannot now be verified from any
original Manuscript extant. These copies, at any rate neither give
us the original order of the texts, as written by Leonardo, nor do
they afford any substitute, by connecting them on a rational scheme;