The Nots, vol 1 | Page 4

press, I have had the advantage of
valuable advice from the Commendatore Giov. Morelli, Senatore del
Regno, and from Signor Gustavo Frizzoni, of Milan. The translation,
under many difficulties, of the Italian text into English, is mainly due to
Mrs. R. C. Bell; while the rendering of several of the most puzzling and
important passages, particularly in the second half of Vol. I, I owe to
the indefatigable interest taken in this work by Mr. E. J. Poynter R. A.
Finally I must express my thanks to Mr. Alfred Marks, of Long Ditton,
who has most kindly assisted me throughout in the revision of the proof
sheets.

The notes and dissertations on the texts on Architecture in Vol. II I owe
to my friend Baron Henri de Geymuller, of Paris.
I may further mention with regard to the illustrations, that the negatives
for the production of the "photo-gravures" by Monsieur Dujardin of
Paris were all taken direct from the originals.
It is scarcely necessary to add that most of the drawings here
reproduced in facsimile have never been published before. As I am now,
on the termination of a work of several years' duration, in a position to
review the general tenour of Leonardos writings, I may perhaps be
permitted to add a word as to my own estimate of the value of their
contents. I have already shown that it is due to nothing but a fortuitous
succession of unfortunate circumstances, that we should not, long since,
have known Leonardo, not merely as a Painter, but as an Author, a
Philosopher, and a Naturalist. There can be no doubt that in more than
one department his principles and discoveries were infinitely more in
accord with the teachings of modern science, than with the views of his
contemporaries. For this reason his extraordinary gifts and merits are
far more likely to be appreciated in our own time than they could have
been during the preceding centuries. He has been unjustly accused of
having squandered his powers, by beginning a variety of studies and
then, having hardly begun, throwing them aside. The truth is that the
labours of three centuries have hardly sufficed for the elucidation of
some of the problems which occupied his mighty mind.
Alexander von Humboldt has borne witness that "he was the first to
start on the road towards the point where all the impressions of our
senses converge in the idea of the Unity of Nature" Nay, yet more may
be said. The very words which are inscribed on the monument of
Alexander von Humboldt himself, at Berlin, are perhaps the most
appropriate in which we can sum up our estimate of Leonardo's genius:
"Majestati naturae par ingenium."
LONDON, April 1883.
F. P. R.

CONTENTS OF VOLUME I.

PROLEGOMENA AND GENERAL INTRODUCTION TO THE
BOOK ON PAINTING

Clavis Sigillorum and Index of Manuscripts.--The author's intention to
publish his MSS. (1).--The preparation of the MSS. for publication
(2).--Admonition to readers (3).--The disorder in the MSS.
(4).--Suggestions for the arrangement of MSS. treating of particular
subjects (5--8).--General introductions to the book on painting
(9--13).--The plan of the book on painting (14--17).--The use of the
book on painting (18).--Necessity of theoretical knowledge (19,
20).--The function of the eye (21--23).--Variability of the eye
(24).--Focus of sight (25).--Differences of perception by one eye and
by both eyes (26--29).--The comparative size of the image depends on
the amount of light (30--39).
II.
LINEAR PERSPECTIVE
General remarks on perspective (40--41).--The elements of
perspective:--of the point (42--46).--Of the line (47--48).--The nature of
the outline (49).--Definition of perspective (50).--The perception of the
object depends on the direction of the eye (51).--Experimental proof of
the existence of the pyramid of sight (52--55).--The relations of the
distance point to the vanishing point (55--56).--How to measure the
pyramid of vision (57).--The production of the pyramid of vision
(58--64).--Proof by experiment (65--66).--General conclusions
(67).--That the contrary is impossible (68).--A parallel case (69).--The
function of the eye, as explained by the camera obscura (70--71).--The
practice of perspective (72--73).--Refraction of the rays falling upon
the eye (74--75).--The inversion of the images (76).--The intersection
of the rays (77--82).--Demonstration of perspective by means of a
vertical glass plane (83--85.)--The angle of sight varies with the
distance (86--88).--Opposite pyramids in juxtaposition (89).--On
simple and complex perspective (90).--The proper distance of objects
from the eye (91--92).--The relative size of objects with regard to their
distance from the eye (93--98).--The apparent size of objects denned by
calculation (99--106).--On natural perspective (107--109).
III.
SIX BOOKS ON LIGHT AND SHADE
GENERAL INTRODUCTION.--Prolegomena (110).--Scheme of the
books on light and shade (111).--Different principles and plans of
treatment (112--116).--Different sorts of light (117--118).--Definition

of the nature of shadows (119--122).--Of the various kinds of shadows
(123--125).--Of the various kinds of light (126--127).--General remarks
(128--129).--FIRST BOOK ON LIGHT AND SHADE.--On the nature
of