Usucapio in the jus civile hinges on possession, and ownership by the jus naturale may take its origin in possession.
In Rome it was a corollary of the doctrine of the existence of a jus naturale.
While he sets forth the jus civile, his exposition and approval follow the dictates of the jus naturale.
And then adds: By its authority the jus naturale prevails over custom and constitution.
Whatever in customs or writings is contrary to the jus naturale is to be held vain and invalid.
This lex naturalis (or jus naturale) is a true promulgated law, since God implants it for recognition in the minds of men.