Metempsychosis is a concept in Greek philosophy related to reincarnation and the transmigration of the soul. It is the idea that, when a person dies, his or her soul is transferred into another body, either another human body or the body of an animal. There is nothing biblical about metempsychosis.
The theory of metempsychosis originated with Pythagoras and his teacher, Pherecydes of Syros, but the popularization of the concept is due to its adoption by Plato. According to Plato’s view, there is a fixed number of souls in existence, and those souls transmigrate in and out of human and animal bodies, never being destroyed. These souls sometimes travel to another, immortal realm, before returning to the mortal realm, bringing back knowledge. In Plato’s Republic, the soul of a warrior named Er travels to heaven and sees the souls of the dead choosing new bodies. Er sees tame animals choosing to be wild and vice versa, men choosing to be birds, birds choosing to become men, gods choosing to become athletes. Once the soul had made its choice, it drank of the River Lethe and was shot down to earth like a star to be born.
Scholars are not sure whether Plato actually believed in metempsychosis or whether his tales were meant to be allegorical. Metempsychosis is unlike reincarnation in that metempsychosis is based on the desire of the soul for new experiences rather than a result of judgment. In the theory of reincarnation, one’s good or bad actions in life determine the nature of the body assigned in the next life. Metempsychosis fits well with Greek philosophy and mythology as a whole; in the Greek myths, gods often take on a human and animal form to achieve their ends.
The idea of metempsychosis or reincarnation does not exist in the Bible. At times, spiritual beings took the form of men or animals to influence humankind. Satan appeared to Eve as a serpent in order to engineer the fall of man (Genesis 3:1–7). The holy angels sometimes appeared as men (Mark 16:5). And it seems that fallen angels once took on the form of men in order to procreate with human women and produce giant, evil offspring called Nephilim (Genesis 6:1–4). But none of this can be considered metempsychosis.
The Bible teaches that each human soul has one life; after death, the soul faces judgment (Hebrews 9:27). There is no coming back in another body of any form for any reason. Jesus gives a wise perspective: “I will show you whom you should fear: Fear him who, after your body has been killed, has authority to throw you into hell. Yes, I tell you, fear him” (Luke 12:5).