Various Authors, Collection of Calculation Texts, 1472 (RV I.I.17 preziosi)

Rare paper manuscript, typical example of a book of "abacus". The typology and year of writing, completed on October 12, 1472, render it very useful, also in terms of studies of Leonardo, despite the fact that it was not among the books in his library. Indeed, it seems quite probable that in his youth Leonardo had undertaken the reading of very similar books, written in the vernacular, which confirms the intended audience of the merchant classes. However, the splendour of the original binding suggests that the booklet may have been intended for a reader from a higher social class than that of Leonardo, who was the illegitimate son of a notary.