1494, he wrote the book.10 And what a book it was: Summa de arithmetica, geometria, proportioni et proportionalita was an enormous survey of everything that was known about mathematics—615 large and densely typeset pages. Amid this colossal textbook, Pacioli included twenty-seven pages that are regarded by many as the most influential work in the history of capitalism. It was the first description of double-entry bookkeeping to be set out clearly, in detail, and with plenty of examples.
