Summa Theologica

Aquinas examines how God created the various parts of the universe and distinguished them from each other. The main points are:

1.  There was no point at which matter was utterly formless, but scripture describes ways in which creation in the beginning was formless in the sense of lacking beauty and light.

2.  There are two different types of prime matter: that which forms the heavenly bodies (incorruptible) and that which forms the earth (corruptible).

3.  The empyrean heaven (the highest part of heaven, where the blessed dwell) existed from the beginning of creation.

4.  Time was created at the very beginning of creation along with matter.

Aquinas proceeds through the six days of creation. First, he considers the meaning of light as it is used in scripture, such as “And God said, let there be light,” and biblical language that applies light to spiritual realities (Christ is the light of the world). The second example shows that light has a spiritual dimension in addition to a material one, referring to the illumination of knowledge that comes from God.

Light is an active quality—an accidental category of being—derived from the substantial form of the sun, filling the air and giving warmth. It is fitting that the creation of light is assigned to the first day of creation, because light is the necessary precondition for creating day and for manifesting creation. 

Aquinas makes the following points: The heavenly firmament was made on the second day of creation; there are waters above the firmament; and there are three heavens. However, Aquinas concedes that a number of different opinions exist on what precisely scripture means by “firmament” and suggests adopting a flexible view. The author of Genesis presented things that would appeal most directly to the senses of his readers. 

Aquinas deals with the gathering together of the waters and the production of plants. By the third day, God has created the prime matter from which the world will be formed; therefore, Genesis speaks of it as “gathering together” instead of “making.”

Aquinas sees the third day as part of a process of completion or remedying a lack that existed before. The waters are gathered together in order to distinguish dry land from water, thus remedying the “void” that existed before. Similarly, plants are created in order to make up for the former “emptiness” or shapelessness. 

Aquinas distinguishes two parts or phases in the work of creation: distinction and adornment. The creation of the heavenly luminaries (the sun, moon, and stars) belong to the phase of adornment, along with the creation of the animals. This is because the work of distinction (in which the elements that make up the universe were formed and distinguished from each other) concerns what is intrinsically essential to the world, and so it was done first.

The heavenly bodies perform a number of functions: They illumine the rest of creation, and thus aid man’s knowledge; they create the variety of seasons; and they act as “signs” to indicate the weather.

There are more aspects to the purpose and function of the various parts of creation than are touched upon by Genesis, because the author was concerned with preventing idolatry and nature worship. 

Both this and Question 72 are unusual in that they consist of a single article. Here, Aquinas’ main point is to consider whether the account of the fifth day of creation is consistent with the medieval understanding of science. Aquinas examines the current theory of how life is generated and concludes that the Genesis account is consistent in communicating the theological, as opposed to scientific, message that the author intended. In this framework of understanding creation, the active principle in creation is the Word of God, not any natural force. 

Similar to the previous Question, Aquinas concludes that the Genesis account of the sixth day (which includes the creation of the cattle and beasts) is consistent with the message it intends to convey.

Land animals are of a higher nature than birds and fish because of their greater mobility and more complex reproduction. According to the medieval understanding, the lower animals are produced from the earth and the water, while man is produced immediately by God. This reinforces the idea that animals show their varying remoteness from God, with man being closest to him as created “in his image and likeness.”

Aquinas addresses the question of why a good God would have created animals that are harmful to man, prior to man’s having sinned. He concludes that the good of the world requires a great diversity of things working together, and that even things harmful to man serve a purpose in the greater scheme of the universe. Furthermore, before he sinned man would have known how to use all things in such a way as not to cause harm. 

Aquinas concludes his survey of the days of creation with the seventh day, God’s day of rest.

The seventh day represents the completion and blessing of God’s creation and his rest from his work. Aquinas refines these concepts, explaining that God does not rest in his works, since he is sufficient in himself, but rather rests from his labors, which refer to a spiritual operation. God blessed and sanctified the seventh day. Because of this, God’s rest accrues to human beings as a blessing.

The seventh day marks the point at which God has instituted all species and creatures. After this, God does not create any new creatures yet continues, through his Providence, to sustain his works in their existence and oversee their propagation. This Question is important because it contains a justification for the Christian observance of the sabbath. 

In this final section, Aquinas deals with miscellaneous objections about the Genesis creation account and shows that Genesis is balanced and consistent in its language. Relying especially on Augustine’s analysis of the creation, Aquinas deals with the question of how literally the days are meant to be taken and whether the ordering of events is appropriate.