Of the Production of Man From Man as to the Soul
Of the Production of Man From Man as to the Soul — St. Thomas Aquinas asks: Whether the sensitive soul is transmitted with the semen?; Whether the intellectual soul is produced from the semen?; Whether human souls were created together at the beginning of the world?.
We next consider the production of man from man: first, as to the soul; secondly, as to the body.
Under the first head there are three points of inquiry:
Article 1: Whether the sensitive soul is transmitted with the semen?
The power in the semen is to the animal seminally generated, as the power in the elements of the world is to animals produced from these elements---for instance by putrefaction. But in the latter animals the soul is produced by the elemental power, according to Gn. 1:20: "Let the waters bring forth the creeping creatures having life." Therefore also the souls of animals seminally generated are produced by the seminal power.
Some have held that the sensitive souls of animals are created by God (). This opinion would hold if the sensitive soul were subsistent, having being and operation of itself. For thus, as having being and operation of itself, to be made would needs be proper to it. And since a simple and subsistent thing cannot be made except by creation, it would follow that the sensitive soul would arrive at existence by creation.
But this principle is false---namely, that being and operation are proper to the sensitive soul, as has been made clear above (): for it would not cease to exist when the body perishes. Since, therefore, it is not a subsistent form, its relation to existence is that of the corporeal forms, to which existence does not belong as proper to them, but which are said to exist forasmuch as the subsistent composites exist through them.
Wherefore to be made is proper to composites. And since the generator is like the generated, it follows of necessity that both the sensitive soul, and all other like forms are naturally brought into existence by certain corporeal agents that reduce the matter from potentiality to act, through some corporeal power of which they are possessed.
Now the more powerful an agent, the greater scope its action has: for instance, the hotter a body, the greater the distance to which its heat carries. Therefore bodies not endowed with life, which are the lowest in the order of nature, generate their like, not through some medium, but by themselves; thus fire by itself generates fire. But living bodies, as being more powerful, act so as to generate their like, both without and with a medium. Without a medium---in the work of nutrition, in which flesh generates flesh: with a medium---in the act of generation, because the semen of the animal or plant derives a certain active force from the soul of the generator, just as the instrument derives a certain motive power from the principal agent. And as it matters not whether we say that something is moved by the instrument or by the principal agent, so neither does it matter whether we say that the soul of the generated is caused by the soul of the generator, or by some seminal power derived therefrom.
Article 2: Whether the intellectual soul is produced from the semen?
It is written in De Eccl. Dogmat. xiv that "the rational soul is not engendered by coition."
It is impossible for an active power existing in matter to extend its action to the production of an immaterial effect. Now it is manifest that the intellectual principle in man transcends matter; for it has an operation in which the body takes no part whatever. It is therefore impossible for the seminal power to produce the intellectual principle.
Again, the seminal power acts by virtue of the soul of the begetter according as the soul of the begetter is the act of the body, making use of the body in its operation. Now the body has nothing whatever to do in the operation of the intellect. Therefore the power of the intellectual principle, as intellectual, cannot reach the semen. Hence the Philosopher says (De Gener. Animal. ii, 3): "It follows that the intellect alone comes from without."
Again, since the intellectual soul has an operation independent of the body, it is subsistent, as proved above (): therefore to be and to be made are proper to it. Moreover, since it is an immaterial substance it cannot be caused through generation, but only through creation by God. Therefore to hold that the intellectual soul is caused by the begetter, is nothing else than to hold the soul to be non-subsistent and consequently to perish with the body. It is therefore heretical to say that the intellectual soul is transmitted with the semen.
Article 3: Whether human souls were created together at the beginning of the world?
It is said (De Eccl. Dogmat. xiv, xviii) that "the soul is created together with the body."
Some have maintained that it is accidental to the intellectual soul to be united to the body, asserting that the soul is of the same nature as those spiritual substances which are not united to a body. These, therefore, stated that the souls of men were created together with the angels at the beginning. But this statement is false. Firstly, in the very principle on which it is based. For if it were accidental to the soul to be united to the body, it would follow that man who results from this union is a being by accident; or that the soul is a man, which is false, as proved above (). Moreover, that the human soul is not of the same nature as the angels, is proved from the different mode of understanding, as shown above (; ): for man understands through receiving from the senses, and turning to phantasms, as stated above (; ). For this reason the soul needs to be united to the body, which is necessary to it for the operation of the sensitive part: whereas this cannot be said of an angel.
Secondly, this statement can be proved to be false in itself. For if it is natural to the soul to be united to the body, it is unnatural to it to be without a body, and as long as it is without a body it is deprived of its natural perfection. Now it was not fitting that God should begin His work with things imperfect and unnatural, for He did not make man without a hand or a foot, which are natural parts of a man. Much less, therefore, did He make the soul without a body.
But if someone say that it is not natural to the soul to be united to the body, he must give the reason why it is united to a body. And the reason must be either because the soul so willed, or for some other reason. If because the soul willed it---this seems incongruous. First, because it would be unreasonable of the soul to wish to be united to the body, if it did not need the body: for if it did need it, it would be natural for it to be united to it, since "nature does not fail in what is necessary." Secondly, because there would be no reason why, having been created from the beginning of the world, the soul should, after such a long time, come to wish to be united to the body. For a spiritual substance is above time, and superior to the heavenly revolutions. Thirdly, because it would seem that this body was united to this soul by chance: since for this union to take place two wills would have to concur---to wit, that of the incoming soul, and that of the begetter. If, however, this union be neither voluntary nor natural on the part of the soul, then it must be the result of some violent cause, and to the soul would have something of a penal and afflicting nature. This is in keeping with the opinion of Origen, who held that souls were embodies in punishment of sin. Since, therefore, all these opinions are unreasonable, we must simply confess that souls were not created before bodies, but are created at the same time as they are infused into them.