Works of St. Anselm, tr. by Sidney Norton Deane, [1903], at sacred-texts.com
How he justly punishes and justly spares the wicked. ‑‑God, in sparing the wicked, is just, according to his own nature because he does what is consistent with his goodness; but he is not just, according to our nature, because he does not inflict the punishment deserved.
BUT it is also just that thou shouldst punish the wicked. For what is more just than that the good should receive goods, and the evil, evils? How, then, is it just that thou shouldst punish the wicked, and, at the same time, spare the wicked? Or, in one way, dost thou justly punish, and, in another, justly spare them? For, when thou punishest the wicked, it is just, because it is consistent with their deserts; and when, on the other hand, thou sparest the wicked, it is just, not because it is compatible with their deserts, but because it is compatible with thy goodness.
For, in sparing the wicked, thou art as just, according to thy nature, but not according to ours, as thou art compassionate, according to our nature, and not according to thine; seeing that, as in saving us, whom it would be just for thee to destroy, thou art compassionate, not because thou feelest an affection (affectum), but because we feel the effect (effectum); so thou art just, not because thou requitest us as we deserve, but because thou dost that which becomes thee as the supremely good Being. In this way, therefore, without contradiction thou dost justly punish and justly spare.