Niels Stensen (Nicolaus Steno; 1638-1686) was son of a goldsmith in Copenhagen. He studied medicine in his native town. In 1660 he went to Amsterdam, where on dissecting the head of a sheep he discovered the parotid duct. An awkward dispute about priority with his teacher Blasius prompted a move to Leiden, where he worked on glands and muscles. In 1664 having failed to obtain an appointment in Copenhagen, he travelled to France and finally Florence, where the Medici dynasty paid him to teach and study not only anatomy but also geology. His interests gradually shifted to spiritual matters: in 1667 he converted to Catholicism, in 1675 (after an unsatisfactory interlude in Copenhagen) he was received into the priesthood. From 1677 until his death in 1686 he served as a travelling bishop in Northern Germany. He was beatified by the Pope in 1988.