Giuseppe Bossi

In 1807 Eugène de Beauharnais, Napoleon's stepson and viceroy of Italy, decided that Leonardo's Last Supper should be copied in mosaic. The wall itself was half lost by then, and the version the mosaicist would work from had to be made by someone able to read what was left. The job went to Giuseppe Bossi, who spent two years on a full-size copy. The mosaic, cut by Giacomo Raffaelli, went to Vienna and is still in the Minoritenkirche there.

The copying turned into research. In 1810 Bossi published Del Cenacolo di Leonardo da Vinci, a book on the painting's sources, its technique and its ruin. Goethe read it in Weimar and wrote a long essay about it, which carried Bossi's findings to German readers.

By then he had already done the thing Milan remembers him for. As secretary of the Brera academy from 1801 he worked to keep the pictures of the churches and convents that Napoleon's government was closing down in the city rather than let them be sold abroad, and the collection he gathered became the Pinacoteca di Brera.

Bossi died in Milan in 1815, at 38. His own drawings and prints ran to more than 3,000 sheets, and in 1822 they were bought by the academy in Venice, Leonardo's study of a man in a circle and a square among them.