It is also needful that thou shouldst know that the Kabbalists believe
in metempsychosis from the body of one species into the body of another
species. Thou hast already been informed of the mystery of clean and
unclean animals; and some of the later sages of the Kabbalah say that
the soul of an unclean person will transmigrate into an unclean animal,
or into abominable creeping things or reptiles. For one form of
uncleanness the soul will be invested with the body of a Gentile, who
will (eventually) become a proselyte; for another, the soul will pass
into the body of a mule; for others, it transmigrates into an ass, a
woman of Ashdod, a bat, a rabbit or a hare, a she-mule or a camel.
Ishmael transmigrated first into the she-ass of Balaam, and subsequently
into the ass of Rabbi Pinchas ben Yair.
THE KABBALA, _Nishmath Chaim_, chap. 13, no. 14.