Ungenerated

When Socrates asserts that “no other thing” but soul is capable of self-motion, this fact confers necessity on soul being “ungenerated and immortal.”

Surely then whatever is ungenerated and in being must be eternal, and whatever is indestructible and in being must equally be so.

So there must be per se causes for the things that come to be. And even if those causes are generated, there must be other per se causes for them as well, until we come to the ungenerated ones.