FOREWORD.

It will be noted that from the perspective of the beauty of the work, progress has been made by Mr. Quantin Albert Quantin (1850–1933), a famous French printer and publisher known for high-quality art books, specifically the direct printing of photographic transfers replacing the previous method of pasting, and that these transfers are even closer to perfection than those of Manuscript A.

To the transcription of the texts, I have thought it useful to add a transcription of the letters that accompany a great number of figures, in cases where these letters would be difficult to find in the facsimile.

For Manuscript D, I hesitated on the manner of transcribing the figures and the commentaries that accompany them in the margin; but, all things considered, it seemed to me that the best course of action would be to reproduce, in general, first everything that is written on the right in the margin, provided that I warn the reader here that they must always take into account the position—which is easy to find—that the figures or texts printed first in small characters occupy laterally on the facsimiles in relation to the main texts.

Finally, for each of the manuscripts B and D, I have compiled an alphabetical table of contents, perhaps even more complete than that of Manuscript A, in which the corrections noted in the Errata have been taken into account, and which it would be well to compare with the latter.

The pagination of Manuscript B has not been transcribed as it was for Manuscripts A and D, because it did not appear to me to be in Leonardo's own hand autograph: a manuscript or signature written by the author themselves. The same applies to a certain number of words written in the ordinary direction Leonardo famously wrote in "mirror script," from right to left; "ordinary direction" refers to standard left-to-right writing on various pages, which are transcriptions by several hands in the Spanish and Italian languages.