Part I of three parts, showing life begins at conception. What follows from this truth is not taken up, but is anyway obvious.
1 Now, since the same things are found both to begin to be and to end, someone might suppose that, because the human soul will not cease to exist, neither will it have begun to exist, but, on the contrary, has always been. And it would seem possible to prove this by the following arguments.
Notes Be careful, here is where the counter-arguments begin (some of which are very clever); to be answered later. And please don’t forget God never started to exist: He always was; He is outside time. Paragraph 5 shows the peril of amateur exegesis.
2 That which will never cease to be has the power to exist forever. But no such thing can ever be truly said not to be; for the extent of a thing’s existential duration is exactly commensurate with its power of existing. But of every thing which had begun to exist, it is at some time true to say that it is not. Therefore, that which will never cease to exist, at no time begins to be.
3 Moreover, just as the truth of intelligible things is imperishable, so is that truth, of itself, eternal; because it is necessary, and whatever is necessary is eternal, for what is necessary to be cannot possibly not be. Now, the imperishable being of the soul is demonstrated from the imperishability of intelligible truth. Hence, by the same reasoning, the soul’s eternity can be proved from the eternal being of intelligible both.
4 Also, a thing that lacks several of its principal parts is not perfect. But, clearly, the principal parts of the universe are intellectual substances, in the genus of which human souls belong, as we have shown above. If every day as many human souls begin to exist as men are born, then, obviously, many of the principal parts of the universe are added to it daily, so that it lacks a multiplicity of things. Consequently, the universe is imperfect. But this is impossible.
5 Then, too, some draw their arguments from the authority of Sacred Scripture. For in Genesis (2:2) it is said that “on the seventh day God ended His work which He had made: and He rested from all His work which He had done.” But, if God made new souls every day, this would not be true. Therefore, no new human souls ever begin to exist, but they have existed from the beginning of the world.
6 Hence, for these and similar reasons, proponents of the doctrine of the world’s eternity have said that, just as the human soul is incorruptible, so has it existed from all eternity. That is why the upholders of the theory of the immortality of human souls in their multiple existence—I refer to the Platonists—asserted that they have existed from eternity, and are united to bodies at one time and separated from them at another, these vicissitudes following a fixed cyclical pattern throughout set periods of years.
Advocates of the theory that human souls are immortal in respect of some single reality, pertaining to all men, which remains after death, declared, however, that this one entity has endured from all eternity; whether it be the agent intellect alone, as Alexander held, or, together with this, the possible intellect, as Averroes maintained. Aristotle, also, seems to be making the same point when, speaking of the intellect, he says that it is not only incorruptible, but also everlasting.
7 On the other hand, some who profess the Catholic faith, yet are imbued with the teachings of the Platonists, have taken a middle position. For, since the Catholic faith teaches that nothing is eternal except God, these persons maintain, not that human souls are eternal, but that they were created with, or rather before, the visible world, yet are fettered to bodies anew. Among these Christians, Origen was the first exponent of this theory, and a number of his disciples followed suit. The theory, indeed, survives to this day among heretics, the Manicheans, for example, siding with Plato in proclaiming the eternity and transmutation of souls.
8 Now, all these opinions can be easily shown to have no foundation in truth. For it has already been proved that there does not exist only one possible agent intellect for all men. Hence, it remains for us to proceed against those theories which, while envisaging the existence of many human souls, maintain that they existed before bodies, either from eternity, or from the foundation of the world. The incongruity of such a notion is exposed by the following arguments.
9 For, it has already been established that the soul is united to the body as its form and act. Now, although act is prior in its nature to potentiality, nevertheless in one and the same thing it is temporally posterior to it; for a thing is moved from potentiality to act. Thus, seed, which is potentially living, preceded the soul, which is the act of life.
Notes Slow down and read that twice. Act is prior in its nature to potentiality, yet potentiality is temporally prior to act.
10 Moreover, it is natural to every form to be united to its proper matter; otherwise, that which is made of form and matter would be something preternatural. But that which befits a thing naturally is attributed to it before that which befits it preternaturally, because the latter is in it by accident, the former, through itself. Now, that which is by accident is always posterior to that which is through itself. It is, therefore, becoming to the soul to be united to the body before being separated from it. The soul, then, was not created before the body to which it is united.
11 Again, every part existing in separation from its whole is imperfect. Now, the soul, being a form, as has been proved, is a part of the specific nature of man. Hence, as long as it exists through itself apart from the body, it is imperfect. But in the order of natural things, the perfect is prior to the imperfect. It would, therefore, be inconsistent with the order of nature were the soul created apart from the body before being united to it.
Note Yet the soul, your intellectual form, persists after the corruption of the body. Hence to reattain its perfection requires a resurrection.
12 And again, if souls are created without bodies, it must be asked how they are united to bodies. This union could he effected in but two ways: by violence or by nature. Now, everything violent is against nature, so that if the union of soul and body is brought about by violence it is not natural. Hence, man, who is composed of both, is something unnatural; which is obviously false. There is also the consideration that intellectual substances are of a higher order than the heavenly bodies. But in the latter there is nothing violent or contrary. Much less, therefore, does any such thing exist in intellectual substances.
13 Now, if the union of souls to bodies is natural, then, in their creation, souls had a natural desire to be united to bodies. Now, natural appetite immediately issues in act if no obstacle stands in the way, as we see in the movement of heavy and light bodies; for nature always works in the same way. So, unless something existed to prevent it, souls would have been united to bodies from the very beginning of their creation. But whatever obstructs the realisation of natural appetite does violence to it. That at some time souls existed in separation from bodies was therefore the result of violence. And this is incongruous, not only because in such substances there can be nothing violent, as was shown, but also because the violent and the unnatural, being accidental, cannot be prior to that which is in keeping with nature, nor can they be consequent upon the total species.
Notes “nature always works in the same way”. This is true, of course, only when circumstances are identical.
14 Furthermore, since everything naturally desires its own perfection, it pertains to matter to desire form, and not conversely. But the soul is compared to the body as form to matter, as was shown above. Therefore, the union of the soul to the body is not brought about in response to the desire of the soul, but, rather, of the body.
15 Now, the argument may be raised that union with the body is natural to the soul, as well as separation from it, according to various periods of time. But such a notion seems impossible. For changes that take place naturally in a subject are accidental, such as youth and old age; so that, if its union with, and separation from the body are for the soul natural changes, then union with the body will be an accident of the soul. The human being constituted by this union therefore will not be an essential but an accidental being.