Pre-existence is the belief that an individual has lived a lived before his earthly birth, or that the soul has had a separate existence before its human birth, a belief which is both ancient and modern. The belief was held by the ancient Egyptians, Pythagoreans, Greeks, and is a basic tenet of Hinduism and Buddhism. Plato held that this principle accounted for the individual’s remembrance of Universals. The Theosophists and Anthroposophists assert that both reincarnation and preexistence is an essential part of their belief system. Spiritualists hold divergent opinions: some claim to remember former lives while others do not. A.G.H.
Riland, George, The New Steinerbooks Dictionary of Paranormal, New York, Warner Books, Inc., 1980, p. 228