Paolo dal Pozzo Toscanelli (1397 – 10 May 1482) was an Italian mathematician, astronomer, and cosmographer. Life Paolo dal Pozzo Toscanelli was born in Florence, the son of the physician Domenico Toscanelli. There is no precise information on his education and background. Gustavo Uzielli claimed in 1894 that Toscanelli studied at the University of Padua, but modern authors consider this pure conjecture. Toscanelli is noted for his observations of comets. Among these was the comet of 1456, which was to be named Halley’s Comet after Edmond Halley predicted its return in 1759. Thanks to his long life, his intelligence and his wide interests, Toscanelli was one of the central figures in the intellectual and cultural history of Renaissance Florence in its early years. His circle of friends included Filippo Brunelleschi, the architect of the Florence Cathedral, and the philosopher Marsilio Ficino. He knew the mathematician, writer and architect Leon Battista Alberti, and his closest friend was Cardinal Nicholas of Cusa—himself a wide-ranging intellect and early humanist, who dedicated two short mathematical works in 1445 to Toscanelli, and made himself and Toscanelli the interlocutors in a 1458 dialogue titled On Squaring the Circle (De quadratura circuli). When Nicholas of Cusa was on his death bed in the remote Perugian town of Todi in 1464, Toscanelli traversed 120 miles from Florence to be with him. Toscanelli along with Nicholas of Cusa appears to have belonged to a network of Florentine and Roman intellectuals who searched for and studied Greek mathematical works, along with Filelfo, George of Trebizond, and the humanist Pope Nicholas V, in company with Alberti and Brunelleschi. In 1439, the Greek philosopher Gemistos Plethon, attending the Council of Florence, acquainted Toscanelli with the extensive travels, writings and mapping of the 1st century BC/AD Greek geographer Strabo, hitherto unknown in Italy. Nearly 35 years later, the Italian was to follow up this amplified knowledge. In 1474, Toscanelli sent a letter and a map to his Portuguese correspondent Fernão Martins, priest at the Lisbon Cathedral, detailing a scheme for sailing westwards to reach the Spice Islands and Asia. Fernão Martins delivered his letter to the King Afonso V of Portugal, in his court of Lisbon. The original of this letter was lost, but its existence is known through Toscanelli himself, who later transcribed it along with the map and sent it to Christopher Columbus, who carried them with him during his first