(John Peter de), a learned philosopher and mathematician, was born in 1663; having made great progress in the mathematics and the philosophy of Descartes, he travelled to Geneva, Holland, and France; was successively professor in several universities; and at length was chosen governor to prince Frederic of Hesse-Cassel, nephew to the king of Sweden. He wrote many works, the most esteemed of which are, 1. His Logic, the best edition of which is that of 1741, in 6 vols 8vo; 2. A Treatise on Beauty; 3. A Treatise on the Education of Children, 2 vols 12mo; 4. Several Treatises on Philosophical and Mathematical Subjects, &c. He died at Launanne in 1748.