Leaf from Summa de arithmetica, geometria, proportioni et proportionalita by Luca Pacioli, 1494.We decided to try to identify a random leaf we had in our collection. Obviously from an early book, the type resembles Erhard Ratdolt’s 1484 rotunda (rotunda being a category of blackletter). Two things made this page unusual: complex fractions in the text, and vernacular Italian (as opposed to Latin, the language of most early European books). A search for the chapter heading “Distinctio nona Tractatus primus” led to the discovery that the page is from the first edition of Summa de arithmetica, geometria, proportioni et proportionalita by Luca Pacioli, printed by Paganinus de Paganinis in Venice in1494.

Summary of arithmetic, geometry, proportions and proportionality (as Stanford mathematician Keith Devlin translates the title, was a practical instruction book for 15th/16th century merchants and businessmen, and “the first printed book on algebra in a vernacular language,” according to Professor Delvin. “Summa did for accounting what Liber abbaci did for Hindu-Arabic arithmetic: it made it go mainstream, presenting it in a way that enabled ordinary people (at least those with some facility with numbers) to master the mathematical techniques required for finance and commerce. For that reason, Pacioli is sometimes referred to as ‘the father of accounting.’”

This podcast about blackletter’s recent, controversial history is worth listening to.