So, to continue my mini photo tour of my travels with Double Entry, my researches next took me from Sansepolcro east to Venice. In the 15th century this fairytale city on the lagoon was the busy commercial centre of Europe, its Rialto the Wall Street of Luca Pacioli’s day. It was also the Silicon Valley of his age, the vibrant centre of a revolutionary new communications technology: the printing press.
And it was to Venice that Luca Pacioli went in 1494 to find a printer for his massive Summa de arithmetica, geometria, proportione et proportionalita (‘Everything about arithmetic, geometry, proportion and proportionality’). The Summa was the first mathematical encyclopaedia of the Renaissance, a synthesis of the entire mathematical knowledge of the Mediterranean, including that of ancient Greece, the Arabs and medieval Europeans. It was based largely on Euclid and the work of Leonardo da Pisa (better known today as Fibonacci). It also contains the 27-page treatise on Venetian double-entry bookkeeping for which Pacioli is now known.
With gloved hands I was allowed to leaf through the weighty 1494 edition of Pacioli’s Summa in the Biblioteca Comunale of Sansepolcro. But in Venice at the Biblioteca Nazionale Marciana in the Piazzetta San Marco, I was able to spend days reading the 1494 edition of the Summa. I sat in the silence of the library’s marble reading room with the 500-year-old book propped up before me on a wooden cradle, absorbing as much as I could of Pacioli’s 15th century Italian – exceptionally for his time, Pacioli chose to write in the vernacular rather than in Latin – and copying out its pages on bookkeeping. Next to me an English student sat reading the original letters of Lord Byron.
At the Marciana I was also lucky to find Giovanni Fazzini, an expert on the maths of Renaissance Venice and its famous Scuola di Rialto (Rialto School) where Luca Pacioli studied when he first went to Venice aged 19. Founded in 1408, during the 15th century the Scuola di Rialto attracted students from across Europe who came to Venice to learn mathematics, astronomy, theology and natural philosophy. At the Scuola di Rialto Luca Pacioli studied under Domenico Bragadino, an Aristotelian and Venice’s public reader in mathematics. In a practice dating from 1433, professors and lecturers in Venice were richly paid by the state from rates levied on house rents and business profits, and so the city attracted some of the best minds of Europe.
The publication of the Summa in 1494 made Luca Pacioli famous across Italy. He became one of the most celebrated mathematicians of his age and the first mathematician of Europe to have his portrait painted, an honour equivalent to having a biopic made in Hollywood today. In the 21st century Luca Pacioli’s portrait is known as much for the many unsolved puzzles it poses as for the historical significance of its sitter. Its mysteries will be the subject of my next double entry post.