In all these Augustine does not admit an order of time, but only of origin and nature. Thus the creation of spiritual and corporeal nature without form was first signified under the title of Earth and Water; not that this formless creation preceded formation in time, but only according to origin. Secondly, the formation of the superior bodies is intended by the words: "Let the Firmament be made"; by which we understand the impression of celestial forms in formless matter; in the third place, we have the impression of the terrestrial forms in formless matter, without any precedence of time, but of origin only.
Therefore, when it is said: "Let the waters be gathered together and the dry land appear," this signifies the impression of the substantial form of water by which such motion belonged to it; and that of earth, according to which it became visible. According to other saints, we see in these works likewise an order of duration; for they conceive unformed matter to have preceded formation by time. In this case formless matter must not be understood as being wholly without form, for already there was Heaven, Earth and Water; but the formlessness of matter is to be taken for the absence of variety, beauty and finish. According to these commentators, Scripture indicates three kinds of want of form: in the heavens, which are the superior, there was darkness, because from thence is the origin of light; to the waters the name of abyss is given to indicate their inordinate immensity; while the earth is described as formless and void, because it was covered with water.
Thus on the First Day the first bodies were formed; on the Second Day, the waters, with the firmament; on the Third Day, the earth, since it was uncovered and appeared dry. On this Day, also, the formlessness of the earth was taken away by the gathering together of the waters, and by the adornment of plants, which left it no longer void. These, according to Augustine, were only created causally; according to others, they were produced in their species; but the opinion of Augustine is founded upon Scripture: "In the day when God made heaven and earth and every seed of the field before it sprang in the earth," etc. It may also be proved by reason. For in the first Days God created causally, and afterwards rested from His works, which He nevertheless continued in another manner by the administration of the things which He had created, and by the work of propagation. Others consider that the first institution of species belongs to the work of the six Days, while the generation of like species, proceeding from the first, belongs to the work of administration; to point out which Scripture says: "Let the earth bring forth the green herb and things producing seed," i.e. the species of plants perfectly produced, from which others proceed.
- text taken from Compendium of the Summa Theologica of Saint Thomas Aquinas, by Bishop Berardus Bongiovanni