named Zalmoxis. Conversely, Clement of Alexandria believed Pythagoras himself had learned it from the Celts and not the opposite, claiming he had been taught by Galatian Gauls, Hindu priests and Zoroastrians. However, author T. D. Kendrick rejected a real connection between Pythagoras and the Celtic idea reincarnation, noting their beliefs to have substantial differences, and any contact to be historically unlikely. Nonetheless, he proposed the possibility of an ancient common source, also related to the Orphic religion and Thracian systems of belief. Germanic paganism Surviving texts indicate that there was a belief in rebirth in Germanic paganism. Examples include figures from eddic poetry and sagas, potentially by way of a process of naming and/or through the family line. Scholars have discussed the implications of these attestations and proposed theories regarding belief in reincarnation among the Germanic peoples prior to Christianization and potentially to some extent in folk belief thereafter. Judaism The belief in reincarnation developed among Jewish mystics in the Medieval World, among whom differing explanations were given of the afterlife, although with a universal belief in an immortal soul. It was explicitly rejected by Saadiah Gaon. Today, reincarnation is an esoteric belief within many streams of modern Judaism. Kabbalah teaches a belief in gilgul, transmigration of souls, and hence the belief in reincarnation is universal in Hasidic Judaism, which regards the Kabbalah as sacred and authoritative, and is also sometimes held as an esoteric belief within other strains of Orthodox Judaism. In Judaism, the Zohar, first published in the 13th century, discusses reincarnation at length, especially in the Torah portion "Balak." The most comprehensive kabbalistic work on reincarnation, Shaar HaGilgulim, was written by Chaim Vital, based on the teachings of his mentor, the 16th-century kabbalist Isaac Luria, who was said to know the past lives of each person through his semi-prophetic abilities. The 18th-century Lithuanian master scholar and kabbalist, Elijah of Vilna, known as the Vilna Gaon, authored a commentary on the biblical Book of Jonah as an allegory of reincarnation. The practice of conversion to Judaism is sometimes understood within Orthodox Judaism in terms of reincarnation. According to this school of thought in Judaism, when non-Jews are drawn to Judaism, it is because they had been Jews in a former life. Such souls may "wander among nations" through multiple lives, until they find their way back to Judaism, including through finding themselves born in a gentile family with