There is no inconsistency in God's commanding us not to take upon ourselves what belongs to Him alone. For to execute vengeance belongs to none but Him who is Lord of all; for when the powers of the world rightly accomplish this end, God himself does it who appointed them for the purpose.
Anselm of CanterburyBut a problem occurs about nothing. For that from which something is made is a cause of the thing made from it; and, necessarily,every cause contributes some assistance to the effect's existence.
Anselm of Canterbury