Metempsychosis (Gr. , denoting change, and soul), the supposed transmigration of the soul from one body to another. It is a feature in Brahmanism and Buddhism, which represent the migration after death into the body of a higher or lower animal as a reward of virtue or penalty for vice. The soul may even deteriorate into the vegetable or mineral world. According to Herodotus, the Egyptians were the first to entertain this doctrine. They believed that the soul was clothed successively with the forms of all the animals that live on the earth, and that it then returned after a cycle of 3,000 years into the body of a man, to recommence its eternal pilgrimage. The later Pythagoreans maintained that the soul has a life peculiar to itself, which it enjoyed in common with demons or spirits before its descent to the earth, and that there must be a degree of harmony between the faculties of the soul and the form which it assumes. Plato adopts and treats the doctrine in his "Phnado," maintaining the preexistence of the soul before it appears in man, of which condition it retains dim reminiscences; and after death, according to its peculiar qualities, it seeks and chooses another body. Every soul, according to him, returns to its original source in 10,000 years.
After completing each life it spends 1,000 years in the infernal world in a condition corresponding to that life. The idea appears in the speculations of the Neo-Platonists, and in the cabala of the Jews. Porphyry gave to it its most definite development in Neo-Platonic thought. The cabalists thought that the destiny of every soul was to return into mystical union with the divine substance, but that in order to do this it must first develop all the perfections of which it has the germ within itself. Origen, in his work " On Principles," is supposed to hold this doctrine, to find in it the final cause of creation, and to maintain that God gave existence to the world as a place of purification for those souls which had sinned in heaven; and this explains why the Deity introduced so many apparent imperfections into his work. But Origen's book exists only in the Latin translation, De Prineipiis, by Rufinus, who is believed by modern critics to have altered the original, and to have interpolated some of his own notions.