Pre-existence, preexistence, beforelife, or premortal existence, is the belief that each individual human soul existed before mortal conception, and at some point before birth enters or is placed into the body. Concepts of pre-existence can encompass either the belief that the soul came into existence at some time prior to conception or the belief that the soul is eternal. Alternative positions are traducianism and creationism, which both hold that the individual human soul does not come into existence until conception. It is to be distinguished from preformation, which is about physical existence and applies to all living things. Plato believed in the pre-existence of the soul, which tied in with his innatism. He thought that we are born with knowledge from a previous life that is subdued at birth and must be relearned. He saw all attainment of knowledge not as acquiring new information, but as remembering previously known information.