TO THE MOST SERENE

FRANCESCO MARIA

II, DUKE OF URBINO.

GUIDUBALDO

OF THE MARCHES OF MONTE:

It is now a decade, most Serene Duke, since I brought to light a volume on mechanical matters, manifesting—if I am not mistaken—the true causes of marvelous mechanical effects; in which I embraced, as being more consistent with right reason, some of the older and principal doctrines of the illustrious Greek authors pertaining to the undertaking at hand. Indeed, relying upon these as most solid foundations, I constructed many and various theorems. Because these, although they were armed by myself with the not-invalid supports of demonstrations, nevertheless appeared to many—who perhaps are not very well-versed in investigating the causes of such things—to be entirely new (as I have learned) and almost unheard of, and not sufficiently firm in their opinion, and therefore they did not seem to have satisfied them entirely. Wherefore, as I was considering by what method it might come about that the work I published could win for itself greater favor day by day, it came into my mind that this could not have happened to me more opportunely than if I were to offer them those ancient and otherwise most grave authors who discourse most elegantly on this subject. I supposed that by their most solid teaching, the theorems which were proposed and explained by me would be rendered firmer.