Tertullian

“ Just as no soul is without sin, so neither is any soul without seeds of good. Therefore, when the soul embraces the faith, being renewed in its second birth by water and the power from above, then the veil of its former corruption being taken away, it beholds the light in all its brightness. ”

“ There is, then, besides the evil which supervenes on the soul from the intervention of the evil spirit, an antecedent, and in a certain sense natural, evil which arises from its corrupt origin. For, as we have said before, the corruption of our nature is another nature having a god and father of its own, namely the author of (that) corruption. Still there is a portion of good in the soul, of that original, divine, and genuine good, which is its proper nature. ”

“ As therefore light, when intercepted by an opaque body, still remains, although it is not apparent, by reason of the interposition of so dense a body; so likewise the good in the soul, being weighed down by the evil, is, owing to the obscuring character thereof, either not seen at all, its light being wholly hidden, or else only a stray beam is there visible where it struggles through by an accidental outlet. Thus some men are very bad, and some very good ”