 Suárez believes that imperfection in the sense of lacking something that is due to nature always comes from external causes. A horse without tail is a horse which had its tail removed or was somehow prevented from growing one. But there is nothing capable of making God less than perfect in this sense: nothing can damage him or otherwise interfere with his perfection. God is not vulnerable to imperfection coming from without (DM XXX.1.2). This can be shown a priori, Suárez contends, by reasoning from God’s other attributes. In the first instance, we can deduce God’s perfection from his simplicity; because he is simple, God is non-composite. Since partless entities cannot be partially diminished, but either exist totally or are totally destroyed, it follows that if God is simple, and exists, he must be perfect in the sense of being complete (DM XXX.1.2).