FOREWORD.

Likewise, it will be possible to determine approximately the date at which Leonardo must have written Manuscript D; it was likely when the Treatise on Painting was on the verge of being completed. As for this latter manuscript Manuscript D, much less substantial than the B collection, but which has the advantage over it of not having lost any leaves^1 and of bearing an original pagination, it will suffice to say, to make its value understood, that it is from this work that Venturi drew the passage relating to the camera obscura original: "chambre obscure"; an early optical device that led to the camera (Manuscript D, folio 8. — Venturi, Essay, etc., p. 23).

Of all Leonardo's manuscripts, the one bearing the letter D may appear the most scientific. Is this a reason to think that—as one would only wrongly believe of Manuscript A, as I stated in the Study cited above—notebook D cannot have any interest or utility for art? The opposite is perhaps true. This notebook, which appears to be the fair copy of some of the long-sought drafts on optics and perspective^2, of which Manuscript A provides examples, gives in a form that seems almost definitive in the author's mind a part of the Treatise on Painting^3. It may be through a profound knowledge of the nature of the eye that Leonardo da Vinci wished to begin, in order to establish, according to his way of seeing, the bases of the chapters on perspective, which were to form a part of this Treatise; also, although Manuscript D is primarily related only to optics proper—to the study of the eye in all living beings—it discusses both perspective and painting. Leonardo distinguishes, parenthetically, the painting in use among the painters of his time (which was entirely conventional, according to him) from the true painting, to be founded on the experimental knowledge of the laws and phenomena of perception.

As for Manuscript B, it contains several passages relating to the proportions of man and on the composition of colors, which were written with the Treatise on Painting in view. To show all the interest that it, too, offers to artists, there is no need to recall further the considerations that lead one to think of it what has been recognized as true regarding Manuscript A. It will be enough to announce that many of the figures explaining the texts can count, for their elegance, their finesse, and their energy, among the most beautiful sketches of the great master. One of them may serve as an example: that of a warrior on horseback (folio 46 verso), to be compared with certain sketches of the statue of Francesco Sforza, and the riders of the Battle of Anghiari^4.

For Manuscripts B and D, especially for the first, even more attention and more requested advice have not been able to preserve me absolutely from all errors. Far from desiring that they pass unnoticed, I hasten to give warning of them. Indications of these will be found in the errata following those of Manuscript A. Those which are serious are, moreover, if I am not mistaken, very rare; I point out here, in this regard, the leaves: 3 verso, 4 recto, 7 recto, 9 verso, 12 recto, 13 recto, 15 recto, 18 verso, 20 verso, 23 recto, 35 recto, 36 recto, 40 verso, 54 verso and 63 verso. I have, moreover, done everything in my power so that in all respects the second volume would be superior, and increasingly superior, to the first. I hope that those who can imagine the fatigue I have had to brave and overcome to reach this goal will grant me some benevolent indulgence.

1. See the general preface at the beginning of Volume A (Manuscript B).
2. "In ancient times, Perspective was synonymous with Optics." original Italian: "Anticamente Prospettiva era sinonimo d'Ottica." (Govi, Leonardo as Scientist and Man of Letters — Essay on the works of Leonardo da Vinci, p. 13).
3. This is perhaps the occasion to point out to those who do not yet know it, an important edition of the Treatise on Painting which appeared a short time ago in Germany: Leonardo da Vinci, the Book of Painting according to the Vatican Codex (Urbinas) 1270, edited, translated and explained by Heinrich Ludwig in three volumes; Vienna, 1882, Wilhelm Braumüller. original German title: "das Buch von der Malerei..."
4. See: Leonardo da Vinci and the statue of Francesco Sforza, by L. Courajod, 1879, published by Champion.