Summa Theologica

To create is to make something from nothing. God necessarily creates from nothing; otherwise there would have to be something from which he made things, which he did not create. It is impossible for creatures to create in the proper sense of the term. Human beings cannot cause something to exist, absolutely speaking. God alone creates, in the sense of making something where before there was nothing. Thus, human procreation is a work of nature rather than a work of creation, and indeed presupposes creation.

Aquinas looks at the role of the persons of the Trinity in creation. Properly speaking, the entire Godhead creates. God can also create through the attributes associated with the different persons (knowledge, will, love). The processions of the persons of the Trinity are the prototype of creation inasmuch as they include these attributes. 

Aquinas discusses the relationship between creation and time. Ancient philosophers debated the question of whether the universe existed from eternity—and would always exist. Aristotle held that the world was eternal. Aquinas holds to the creation account in Genesis and counters that the world had a beginning in time, making the universe finite. Aquinas also asserts that time began to exist with the beginning of the universe. Indeed, “nothing except God can be from eternity” (251). 

Aquinas establishes why there are multiple things in the universe instead of only one, and one universe instead of many. Creatures are different—unequal—because God in his goodness makes perfection out of different parts, all contributing to the good of the whole. Aquinas states: “The perfection of the universe requires that there should be inequality in things, so that every grade of goodness may be realized” (260). 

This question delves into the problem of evil and its relation to good. Aquinas asserts, following Augustine, that evil has no being in itself but is simply the corruption, or privation, or absence, of good. The perfection of the universe requires that things should sometimes go wrong, but God can bring greater good out of this evil. As outlined in the previous question, all the parts of the universe are ordered to the good and final end of the whole. 

Evil cannot completely destroy good, though it can diminish it. Thus, repeated sins can distance a soul from God, but they cannot destroy the essential nature of the soul, which is oriented toward good. Every evil can be classified as either a pain or a fault. A pain consists in the withdrawal of the form and integrity of a thing. A fault consists in a failure of action on the part of the will. However, fault is a greater evil than pain. Aquinas lists several ways in which we see this to be true. They include:

God sometimes inflicts or permits temporary pain in order to prevent a fault from being committed. It is fault that makes a person evil; but suffering pain does not make a person evil. The evil of pain takes away a created good (e.g., blindness takes away sight), but the evil of fault is directly opposed to the divine will. As such, it is a more serious evil. 

Aquinas establishes that evil must have a cause. He then states, surprisingly, that good may be said to be the cause of evil. This is because evil attaches itself to good as its subject—in order for evil to exist, it must prey upon good. Evil represents the failure of good to actualize itself properly. Evil follows accidentally from good.

God, the supreme good, is ultimately in control of all things. Evil is not a co-equal power to God. While there are things that are essentially good, there is nothing that is essentially bad, because evil has no independent existence. It is like a parasite that attaches itself to good and seeks to destroy it, but cannot.

We do not say that God causes evil, because he does not will evil for its own sake. Nevertheless, God does permit evils for the sake of the greater good and the perfection of the universe as a whole.