The transmigration of souls, or metempsychosis, is a concept which underpins Plato's ideas concerning innate knowledge. Plato may have incorporated this concept from two Greek religious groups that preceded him: the Pythagoreans or the Orphics. Plato taught that "all learning is but recollection" because we have innate knowledge of universal ideas (e.g., everywhere, a triangle has 3 sides—hence its universality) from the past experiences of our immortal soul. This soul, according to Platonic thought, once separated from the body, spends an indeterminate amount of time in "formland" (see The Allegory of the Cave in The Republic) and then assumes another body. Therefore, according to Plato, we need only recall our buried memories to manifest innate knowledge
Metempsychosis in Greek Philosophy
is unclear how the doctrine of metempsychosis arose in Greece; most
scholars do not believe it was borrowed from Egypt or that it somehow
was transmitted from ancient Hindu thinkers of India. It is easiest to
assume that earlier ideas which had never been extinguished were
utilized for religious and philosophic purposes. The Orphic religion,
which held it, first appeared in Thrace upon the semi-barbarous
north-eastern frontier. Orpheus, its legendary founder, is said to have
taught that soul and body are united by a compact unequally binding on
either; the soul is divine, immortal and aspires to freedom, while the
body holds it in fetters as a prisoner. Death dissolves this compact,
but only to re-imprison the liberated soul after a short time: for the
wheel of birth revolves inexorably. Thus the soul continues its journey,
alternating between a separate unrestrained existence and fresh
reincarnation, round the wide circle of necessity, as the companion of
many bodies of men and animals." To these unfortunate prisoners Orpheus
proclaims the message of liberation, that they stand in need of the
grace of redeeming gods and of Dionysus in particular, and calls them to
turn to God by ascetic piety of life and self-purification: the purer
their lives the higher will be their next reincarnation, until the soul
has completed the spiral ascent of destiny to live for ever as God from
whom it comes. Such was the teaching of Orphism which appeared in Greece
about the 6th century BC, organized itself into private and public
mysteries at Eleusis and elsewhere, and produced a copious literature.
The earliest Greek thinker with whom metempsychosis is connected is Pherecydes; but Pythagoras, who is said to have been his pupil, is its first famous philosophic exponent. Pythagoras probably neither invented the doctrine nor imported it from Egypt, but made his reputation by bringing Orphic doctrine from North-Eastern Hellas to Magna Graecia and by instituting societies for its diffusion.
The real weight and importance of metempsychosis in Western tradition is due to its adoption by Plato. Had he not embodied it in some of his greatest works it would be merely a matter of curious investigation for the Western anthropologist and student of folk-lore. In the eschatological myth which closes the Republic he tells the story how Er, the son of Armenius, miraculously returned to life on the twelfth day after death and recounted the secrets of the other world. After death, he said, he went with others to the place of Judgment and saw the souls returning from heaven and from purgatory, and proceeded with them to a place where they chose new lives, human and animal. He saw the soul of Orpheus changing into a swan, Thamyras becoming a nightingale, musical birds choosing to be men, the soul of Atalanta choosing the honours of an athlete. Men were seen passing into animals and wild and tame animals changing into each other. After their choice the souls drank of Lethe and then shot away like stars to their birth. There are myths and theories to the same effect in other dialogues, the Phaedrus, Meno, Phaedo, Timaeus and Laws. In Plato's view the number of souls was fixed; birth therefore is never the creation of a soul, but only a transmigration from one body to another. Plato's acceptance of the doctrine is characteristic of his sympathy with popular beliefs and desire to incorporate them in a purified form into his system. Aristotle, a far less emotional and sympathetic mind, has a doctrine of immortality totally inconsistent with it.
The idea of metempsychosis was also held by some of the Gnostics, and it became a source of disagreement between them and the leaders of the Christian church. Irenaeus, the second century bishop of Lyons, wrote at length against the Gnostics in his pacesetting Contra Heresies and singled out metem-psychosis as an idea that was incompatible with Christianity. The church has essentially followed Irenaeus's lead in its consideration of metempsychosis and reincarnation.
Origen, a Christian theologian of the third century with a platonic background, tried to defend some aspects of the metempsychosis doctrine, primarily the prior existence of the soul, but soon gave up, having found the idea contrary to the New Testament teachings.
See Also: Transmigration