Select Works, Section 302

Section 15 15. The souls peering forth from the Intellectual Realm descend first to the heavens and there put on a body; this becomes at once the medium by which as they reach out more and more towards magnitude [physical extension] they proceed to bodies progressively more earthy. Some even plunge from heaven to the very lowest of corporeal forms; others pass, stage by stage, too feeble to lift towards the higher the burden they carry, weighed downwards by their heaviness and forgetfulness. As for the differences among them, these are due to variation in the bodies entered, or to the accidents of life, or to upbringing, or to inherent peculiarities of temperament, or to all these influences together, or to specific combinations of them. Then again some have fallen unreservedly into the power of the destiny ruling here: some yielding betimes are betimes too their own: there are those who, while they accept what must be borne, have the strength of self-mastery in all that is left to their own act; they have given themselves to another dispensation: they live by the code of the aggregate of beings, the code which is woven out of the Reason-Principles and all the other causes ruling in the kosmos, out of soul-movements and out of laws springing in the Supreme; a code, therefore, consonant with those higher existences, founded upon them, linking their sequents back to them, keeping unshakeably true all that is capable of holding itself set towards the divine nature, and leading round by all appropriate means whatsoever is less natively apt. In fine all diversity of condition in the lower spheres is determined by the descendent beings themselves.