Louis Bertrand Castel

Louis Bertrand Castel (1688 to 1757) was a French mathematician born in Montpellier, who entered the Jesuit order in 1703. After studying literature he devoted himself entirely to mathematics and natural philosophy. He moved from Toulouse to Paris in 1720 at the request of Bernard de Fontenelle and acted as science editor of the Jesuit Journal de Trévoux. His best-known work in his own time was Optique des couleurs of 1740, a treatise on the melody of colours, and he also wrote Traité de physique sur la pesanteur universelle des corps in 1724, Mathématique universelle in 1728 and a critical account of the system of Isaac Newton in 1743. He wrote on physics, mathematics, morals, aesthetics, theology and history and tried to reconcile fields and viewpoints, basing much of his work on analogical thinking, in which the physical and moral worlds are understood by discovering analogies. He placed humanity at the centre of natural philosophy, holding that humans are embodied spirits whose freely chosen actions affect the world, and he used this emphasis on free will to counter deterministic views of man and nature.