Summa contra Gentiles2.84 Chapter LXXXIV. Solution of the foregoing arguments

The arguments whereby it is proved that souls have existed from eternity, or that, at least, they existed before bodies, are easily solved.

For the first statement, that the soul has the power to be always, must be granted: but it must be observed that the power and potentiality of a thing extend not to what has been, but to what is or will be: wherefore possibility has no place in the past. Therefore from the fact that the soul has the power to be always we may conclude, not that it always was, but that it always will be.

Further. That to which a power is directed does not follow from the power unless the power be supposed. Hence, although the soul has the power to be always, we cannot infer that the soul is always, except after it has already received this power. And if we presume that it received this power from eternity, we shall be begging the question at issue, namely whether the soul has been from eternity.

As to the second objection about the eternity of the truth which the soul understands:—we must observe that the eternity of a truth understood may be taken in two ways: in one way, as to the thing understood; in another as to that whereby it is understood. If the understood truth be eternal as regards the thing understood, it follows that the thing understood is eternal, but not the one who; understands: whereas if the understood truth be eternal as to that whereby it is understood, it would follow that the soul which understands it is eternal. Now the understood truth is eternal not in the latter but in the former way: for it is clear from what has been said that the intelligible species, by which our soul understands truth, are acquired by us from the phantasms through the active intellect. Hence it cannot be inferred that the soul is eternal, but that the truths understood are based on something eternal, for their foundation is in the first truth, as in the universal cause which contains all truth. But the soul is compared to this eternal thing, not as subject to form, but as a thing to its proper end, because the true is the good of the intellect and the end thereof. Now from a thing’s end we can argue about its duration, just as we can argue about its beginning from its efficient cause: since what is directed to an eternal end must be capable of enduring for ever. Consequently, from the eternity of intelligible truth we can prove that the soul is immortal, but not that it is eternal. That neither can the latter be proved from the eternity of the agent is clear from what has been said above when we were discussing the eternity of creatures.

The third objection which refers to the perfection of the universe is not cogent. For the perfection of the universe regards the species, not the individuals: since the universe is continually receiving an addition of individuals to the pre-existing species. Now human souls do not differ specifically among themselves, but only numerically, as we have proved. Consequently it is not inconsistent with the perfection of the universe, if new souls be created.

Hence we may gather the reply to the fourth objection.

For it is stated at the same time (Gen. i.)’ that God ended His work, and that He rested... from all His work which He had done. Since, then, the ending or perfecting of creatures regards the species and not the individuals, so God’s rest must be understood to refer to the cessation from forming new species, but not new individuals, the like of which, in the species, have existed before. Accordingly, as all human souls are of one species, even as are all men, it is not incompatible with the aforesaid rest if God creates new souls from day to day.

It must, however, be observed that we do not find it stated by Aristotle that the human intellect is eternal; and yet he is wont to say this of those things which, in his opinion, always have been. But he declares that it is everlasting; and this can be said of those things that always will be, although they have not always been. Hence (ii Metaph.y in excluding the intellective soul from the conditions of other forms, he did not say that this form was before matter,—and yet Plato said this of ideas, so that it would seem consistent with the subject of which he was treating that he should say something of the kind of the soul,—but he said that it remains after the body.