Stjepan Gradić

Ragusan philosopher and scientist (1613–1683)

Stjepan Gradić, also known as Stefano Gradi (Latin: Stephanus Gradius; 6 March 1613 – 2 May 1683) philosopher, scientist and a patrician of the Republic of Ragusa.

Stijepo's parents were Miho Gradi (Gradić) and Marija Benessa (Beneša). He was born in Ragusa (Dubrovnik), Republic of Ragusa, where he was first schooled. He moved to Rome by the order of his uncle, a vicar general of Ragusa, Petar Benessa. In Rome and in Bologna he studied philosophy, theology, law and mathematics. His mathematics professor in Rome was Bonaventura Cavalieri and in Bologna his mathematics professor was Benedetto Castelli. He became a priest in 1643, the year he returned home and soon became abbot of the Benedictine abbey of St. Cosmas and Damian on the island of Pašman, canon of cathedral choir in Ragusa and Ragusan deputy Archbishop. After a private trip to Rome he remained there until his death as the official diplomatic representative of the Republic of Ragusa to the Holy See. Since 1682 he was the head of the Vatican Library. He was solving many mathematical problems which are left in his own inheritance and correspondence with other mathematicians as well, including those of Ghetaldus such as the first problem from Ghetaldus' work Apollonius redivivus. In scientific correspondence with Giovanni Alfonso Borelli and Honoré Fabri he published works dealing with the natural causes of motion and the laws of acceleration and falling bodies. He wrote on the problem of true and apparent position of the polar star.