Of peasant origin, as a young man studied in Rome where he learned to grind lenses . Thereafter, he became a full-time lens grinder for about 50 years, constructing telescopes and lenses for important persons and for the Royal Observatory in Paris. In 1664 he developed his lens-grinding lathe, with which he made superior lenses for telescopes. With his own instruments he observed the moons of Jupiter and the rings of Saturn in 1664–65