Summa Theologica, Part I · Aquinas Thomas
QUESTION 75
_On the contrary,_ Dionysius says (Div. Nom. iv) that human souls owe to Divine goodness that they are "intellectual," and that they have "an incorruptible substantial life." _I answer that,_ We must assert that the intellectual principle which we call the human soul is incorruptible. For a thing may be corrupted in two ways--_per se,_ and accidentally. Now it is impossible for any substance to be generated or corrupted accidentally, that is, by the generation or corruption of something else. For generation and corruption belong to a thing, just as existence belongs to it, which is acquired by generation and lost by corruption. Therefore, whatever has existence _per se_ cannot be generated or corrupted except "per se"; while things which do not subsist, such as accidents and material forms, acquire existence or lose it through the generation or corruption of composite things. Now it was shown above (AA. 2, 3) that the souls of brutes are not self-subsistent, whereas the human soul is; so that the souls of brutes are corrupted, when their bodies are corrupted; while the human soul could not be corrupted unless it were corrupted _per se._ This, indeed, is impossible, not only as regards the human soul, but also as regards anything subsistent that is a form alone. For it is clear that what belongs to a thing by virtue of itself is inseparable from it; but existence belongs to a form, which is an act, by virtue of itself. Wherefore matter acquires actual existence as it acquires the form; while it is corrupted so far as the form is separated from it. But it is impossible for a form to be separated from itself; and therefore it is impossible for a subsistent form to cease to exist.
Granted even that the soul is composed of matter and form, as some pretend, we should nevertheless have to maintain that it is incorruptible. For corruption is found only where there is contrariety; since generation and corruption are from contraries and into contraries. Wherefore the heavenly bodies, since they have no matter subject to contrariety, are incorruptible. Now there can be no contrariety in the intellectual soul; for it receives according to the manner of its existence, and those things which it receives are without contrariety; for the notions even of contraries are not themselves contrary, since contraries belong to the same knowledge. Therefore it is impossible for the intellectual soul to be corruptible. Moreover we may take a sign of this from the fact that everything naturally aspires to existence after its own manner. Now, in things that have knowledge, desire ensues upon knowledge. The senses indeed do not know existence, except under the conditions of "here" and "now," whereas the intellect apprehends existence absolutely, and for all time; so that everything that has an intellect naturally desires always to exist. But a natural desire cannot be in vain. Therefore every intellectual substance is incorruptible.
Reply Obj. 1: Solomon reasons thus in the person of the foolish, as expressed in the words of Wisdom 2. Therefore the saying that man and animals have a like beginning in generation is true of the body; for all animals alike are made of earth. But it is not true of the soul. For the souls of brutes are produced by some power of the body; whereas the human soul is produced by God. To signify this it is written as to other animals: "Let the earth bring forth the living soul" (Gen. 1:24): while of man it is written (Gen. 2:7) that "He breathed into his face the breath of life." And so in the last chapter of Ecclesiastes (12:7) it is concluded: "(Before) the dust return into its earth from whence it was; and the spirit return to God Who gave it." Again the process of life is alike as to the body, concerning which it is written (Eccles. 3:19): "All things breathe alike," and (Wis. 2:2), "The breath in our nostrils is smoke." But the process is not alike of the soul; for man is intelligent, whereas animals are not. Hence it is false to say: "Man has nothing more than beasts." Thus death comes to both alike as to the body, by not as to the soul.
Reply Obj. 2: As a thing can be created by reason, not of a passive potentiality, but only of the active potentiality of the Creator, Who can produce something out of nothing, so when we say that a thing can be reduced to nothing, we do not imply in the creature a potentiality to non-existence, but in the Creator the power of ceasing to sustain existence. But a thing is said to be corruptible because there is in it a potentiality to non-existence. Reply Obj. 3: To understand through a phantasm is the proper operation of the soul by virtue of its union with the body. After separation from the body it will have another mode of understanding, similar to other substances separated from bodies, as will appear later on (Q. 89, A. 1). _______________________ SEVENTH ARTICLE [I, Q. 75, Art. 7] Whether the Soul Is of the Same Species As an Angel? Objection 1: It would seem that the soul is of the same species as an angel. For each thing is ordained to its proper end by the nature of its species, whence is derived its inclination for that end. But the end of the soul is the same as that of an angel--namely, eternal happiness. Therefore they are of the same species. Obj. 2: Further, the ultimate specific difference is the noblest, because it completes the nature of the species. But there is nothing nobler either in an angel or in the soul than their intellectual nature. Therefore the soul and the angel agree in the ultimate specific difference: therefore they belong to the same species.
Obj. 3: Further, it seems that the soul does not differ from an angel except in its union with the body. But as the body is outside the essence of the soul, it seems that it does not belong to its species. Therefore the soul and angel are of the same species. _On the contrary,_ Things which have different natural operations are of different species. But the natural operations of the soul and of an angel are different; since, as Dionysius says (Div. Nom. vii), "Angelic minds have simple and blessed intelligence, not gathering their knowledge of Divine things from visible things." Subsequently he says the contrary to this of the soul. Therefore the soul and an angel are not of the same species.
_I answer that,_ Origen (Peri Archon iii, 5) held that human souls and angels are all of the same species; and this because he supposed that in these substances the difference of degree was accidental, as resulting from their free-will: as we have seen above (Q. 47, A. 2). But this cannot be; for in incorporeal substances there cannot be diversity of number without diversity of species and inequality of nature; because, as they are not composed of matter and form, but are subsistent forms, it is clear that there is necessarily among them a diversity of species. For a separate form cannot be understood otherwise than as one of a single species; thus, supposing a separate whiteness to exist, it could only be one; forasmuch as one whiteness does not differ from another except as in this or that subject. But diversity of species is always accompanied with a diversity of nature; thus in species of colors one is more perfect than another; and the same applies to other species, because differences which divide a genus are contrary to one another. Contraries, however, are compared to one another as the perfect to the imperfect, since the "principle of contrariety is habit, and privation thereof," as is written, _Metaph._ x (Did. ix, 4).
The same would follow if the aforesaid substances were composed of matter and form. For if the matter of one be distinct from the matter of another, it follows that either the form is the principle of the distinction of matter--that is to say, that the matter is distinct on account of its relation to divers forms; and even then there would result a difference of species and inequality of nature: or else the matter is the principle of the distinction of forms. But one matter cannot be distinct from another, except by a distinction of quantity, which has no place in these incorporeal substances, such as an angel and the soul. So that it is not possible for the angel and the soul to be of the same species. How it is that there can be many souls of one species will be explained later (Q. 76, A. 2, ad 1). Reply Obj. 1: This argument proceeds from the proximate and natural end. Eternal happiness is the ultimate and supernatural end. Reply Obj. 2: The ultimate specific difference is the noblest because it is the most determinate, in the same way as actuality is nobler than potentiality. Thus, however, the intellectual faculty is not the noblest, because it is indeterminate and common to many degrees of intellectuality; as the sensible faculty is common to many degrees in the sensible nature. Hence, as all sensible things are not of one species, so neither are all intellectual things of one species.
Ideas discussed in this chapter
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