Metempsychosis : transmigration of the soul (not an illness).

Metempsychosis has always been the accepted belief of many of the most intelligent members of the ace. It is found to have been the inner doctrine of the ancient Egyptians, and was held in the highest regard by the great thinkers of the ancient Western world, such as Pythagoras, Empedocles, Plato, Virgil, and Ovid. Plato 's teachings were filled with the doctrine. The Hindu philosophies are based upon it. The Persian Magi held implicitly to it. The ancient Druids, and the Priests of Gaul taught it. Traces of the doctrine are found in the records of the ancient races of the Aztecs, the Peruvians, and other old peoples of the New World. The Eleusinian Mysteries of Greece, the Roman Mysteries of the Temple, the Inner Doctrines of the Kabbala of the Hebrews, all were based upon the doctrine of Metempsychosis. The early Christian Fathers, the Gnostics and Manicheans and other early Christian sects, believed in it. The great philosophers, ancient and modern, treated it with respect if indeed they did not fully accept it in many cases.

http://www.sacred-texts.com/sro/sdr/sdr11.htm