Summa contra Gentiles2.87 Chapter LXXXVII. That the human soul is brought into being through creation by God

From what has been said it can be proved that God alone brings the human soul into being.

For whatever is brought into being, is either generated per se or accidentally, or is created. Now the human soul is not generated per se: since it is not composed of matter and form, as shown above. Neither is it generated accidentally: for, since it is the form of the body, it would be generated through the body being generated, which results from the active force in the semen, and this has been disproved. Since then the human soul has a beginning of its existence, for it is neither eternal nor exists before the body, as we have shown, it follows that it comes forth into being by creation. Now we have proved that God alone can create. Therefore He alone brings forth the human soul into being.

Moreover. Everything whose substance is not its being has an author of its being, as shown above. Now the human soul is not its own being: for this is peculiar to God alone, as already proved. Therefore it has an active cause of its being. But that which has being fer se, is also caused fer se: whereas that which has not being per se, but only together with some other thing, is caused, not per se, but through this other thing being caused: thus the form of fire is caused when the fire is made. Now it is proper to the human soul, as compared with other forms, to be subsistent in its own being, and to communicate to the body the being proper to itself. Therefore the human soul has its becoming per se, in contrast to other forms which have their becoming accidentally, through the making of the composite. But, since the human soul has not matter as part of itself, it cannot be made from something. It remains, therefore, that it is made from nothing: and thus it is created. And seeing that creation is the proper work of God, as we proved above, it follows that it is created immediately by God alone.

Eurther. Things belonging to the same genus come into being in the same way, as we proved above.' Now the soul belongs to the genus of intellectual substances: and it is inconceivable that these should come into being save by the way of creation. Therefore the human soul comes into being through creation by God.

Again. Whatsoever is brought into being by an agent, acquires from the latter, either something that is the principle of being in that particular species, or absolute being itself. Now the soul cannot be brought into being in such a way as to acquire something as the principle of its being, as happens in things composed of matter and form, which are generated through acquiring a form in act: because the soul does not contain something in itself by way of principle of its being, for it is a simple substance, as was shown above. Hence it remains that it is not brought into being by an agent except by receiving from it being absolutely. Now being is the proper effect of the first and universal agent: for secondary agents act by impressing the likeness of their forms on the things they make, which likenesses are the forms of the things made. Therefore the soul cannot be brought into being except by the first and universal agent, which is God.

Further. The end of a thing corresponds to its principle: for a thing is perfect when it attains its proper principle, whether by likeness, or in any way whatever. Now the end and ultimate perfection of the human soul is to soar above the whole order of creatures and to reach the First Principle, which is God. Therefore the proper principle of the soul’s origin is God.

We also find this implied in Holy Writ (Gen. i.). For whereas while speaking of the formation of other animals, it ascribes their souls to other causes, for instance when it says Let the waters bring forth the creeping creature with a living soul, and in like manner as to other things; when it comes to man, it indicates the creation of the soul by God, by saying: God formed man of the slime of the earth, and breathed into his face the breath of life.

Hereby is excluded the error of those who hold that souls were created by angels.