OPTIMISM is that philosophical doctrine which, starting from the absolute perfection of Deity, attributes to the universe, his work, the greatest possible perfection. This theory is to be found in some form or other in almost all the great speculative schools of antiquity, and especially among the philosophers of the Academy, of the Porch, and of Alexandria. Anselm and Aquinas were its chief advocates in the middle ages; its grandest developments, however, belong to modern times, and, in particular, to the schools of Descartes and Leibnitz. The splendid scheme of optimism advocated by the latter in his Essais de Théodicée is well known. (See DISSERTATION FIRST, part ii.)