Paolo Toscanelli

Timeline

1. 1397–1430Florence · FlorenceToscanelli was born in Florence and went early to study in Padua, where he formed a friendship with the future cardinal Nicholas of Cusa. After returning home he practiced medicine and studied mathematics and astronomy as a "physicus," becoming a central figure in the intellectual circles of Medicean Florence and taking part in comet observations and discussions of the earth's scale.
2. 1430–1464Florence · FlorenceHe provided mathematical advice on the orientation and measurement of Brunelleschi's great dome and corresponded with Cusa on geometry and cosmology; Cusa's geometric treatise of about 1450 was dedicated to Toscanelli. When Cusa lay dying at Todi in 1464, Toscanelli traveled far to visit him. These connections led him to weave mathematics, medicine, and geographical speculation into a single argument about the navigability of the earth.
3. 1474–1482Florence · FlorenceOn June 25, 1474, he wrote to Fernão Martins, a canon of Lisbon Cathedral, enclosing a map and arguing that one could reach Cathay's court by sailing about 26 degrees west from Lisbon, and Japan by going further west. Columbus later obtained a copy of the letter and similar charts and used them as a key argument for the feasibility of a westward voyage. Toscanelli overestimated Asia's east-west extent, and combined with Columbus's underestimate of the earth's circumference, this led to a miscalculation of the distance. He died in Florence on May 10, 1482.