The Enchiridion 96
96 The Omnipotent God Does Well Even in the Permission of Evil PL 40, 276
Nor can we doubt that God does well even in the permission of what is evil. For He permits it only in the justice of His judgment. And surely all that is just is good. Although, therefore, evil, in so far as it is evil, is not a good; yet the fact that evil as well as good exists, is a good. For if it were not a good that evil should exist, its existence would not be permitted by the omnipotent Good, who without doubt can as easily refuse to permit what He does not wish, as bring about what He does wish. And if we do not believe this, the very first sentence of our creed is endangered, wherein we profess to believe in God the Father Almighty. For He is not truly called Almighty if He cannot do whatsoever He pleases, or if the power of His almighty will is hindered by the will of any creature whatsoever.
Deus facit bene, etiam sinendo fieri male. Nec dubitandum est Deum facere bene, etiam sinendo fieri quaecumque fiunt male. Non enim hoc nisi justo judicio sinit; et profecto bonum est omne quod justum est. Quamvis ergo ea quae mala sunt, in quantum mala sunt, non sint bona; tamen ut non solum bona, sed etiam sint et mala, bonum est. Nam nisi esset hoc bonum, ut essent et mala, nullo modo esse sinerentur ab omnipotente bono: cui procul dubio quam facile est quod vult facere, tam facile est quod non vult esse non sinere. Hoc nisi credamus, periclitatur ipsum nostrae Confessionis initium, qua nos in Deum Patrem omnipotentem credere confitemur. Neque enim ob aliud veraciter vocatur omnipotens, nisi quoniam quidquid vult potest, nec voluntate cujuspiam creaturae voluntatis omnipotentis impeditur effectus.