16. If the soul could not become evil, and if there be but a single
way for the soul to enter the body, and to remain present within it,
there would be no meaning in the periodical "descents" and "ascents"
of the soul, the "chastisements" she undergoes, and the "migration"
into the bodies other (than human bodies, that is, animal ones). Such
(mythological) teachings have indeed been handed down from the ancient
philosophers who best expounded the soul. Now it will be well to show
that our doctrine harmonizes with that which they have taught, or that
at least there is no contradiction between them.