The doctrine of soul immortality was one of the main teachings in ancient Greek phylosophic systems. One of its forms is reincarnation or returning to life in a new body after death. Before Plato the doctrine was mostly based on tradition, and beginning with Plato we can speak about scientific (in the ancient understanding of the word) development of the problem. Nevertheless, Pre-Plato phylosophy is of great interest as a source of this ancient Greek teaching.