Retrato de Luca Pacioli

Luca Pacioli was a Franciscan friar and mathematician who moved to Milan in the 1490s and grew close to Leonardo da Vinci, teaching him proportion while Leonardo drew the diagrams for his book on geometry. This portrait catches him at his table mid-demonstration, one hand on an open Euclid, chalk and compass beside him. Above his shoulder hangs a glass polyhedron of 26 faces, half filled with water, its facets catching a tiny reflection of a palace. The younger man at his side has never been firmly identified. Even the painter is uncertain, the signature reads Jacopo de' Barbari, but scholars have argued for other hands, Leonardo's among them.