Objection 1. It would seem that the sensitive powers remain in the sensitive soul. For Augustine says (De Spir. et Anim. xv): "The soul withdraws from the body taking all with itself, sense and imagination, reason, understanding and intelligence, the concupiscible and irascible powers." Now sense, imagination, concupiscible and irascible are sensitive powers. Therefore the sensitive powers remain in the separated soul.
Objection 2. Further, Augustine says (De Eccl. Dogm. xvi): "We believe that man alone has a substantial soul, which lives though separated from the body, and clings keenly to its senses and wits." Therefore the soul retains its senses after being separated from the body.
Objection 3. Further, the soul's powers are either its essential parts as some maintain, or at least are its natural properties. Now that which is in a thing essentially cannot be separated from it, nor is a subject severed from its natural properties. Therefore it is impossible for the soul to lose any of its powers after being separated from the body.
Objection 4. Further, a whole is not entire if one of its parts be lacking. Now the soul's powers are called its parts. Therefore, if the soul lose any of its powers after death, it will not be entire after death: and this is unfitting.
Objection 5. Further, the soul's powers co-operate in merit more even than the body, since the body is a mere instrument of action, while the powers are principles of action. Now the body must of necessity be rewarded together with the soul, since it co-operated in merit. Much more, therefore, is it necessary that the powers of the soul be rewarded together with it. Therefore the separated soul does not lose them.
Objection 6. Further, if the soul after separation from the body loses its sensitive power, that must needs come to naught. For it cannot be said that it is dissolved into some matter, since it has no matter as a part of itself. Now that which entirely comes to naught is not restored in identity; wherefore at the resurrection the soul will not have the same identical sensitive powers. Now according to the Philosopher (De Anima ii, 1), as the soul is to the body so are the soul's powers to the parts of the body, for instance the sight to the eye. But if it were not identically the same soul that returns to the body, it would not be identically the same man. Therefore for the same reason it would not be identically the same eye, if the visual power were not identically the same; and in like manner no other part would rise again in identity, and consequently neither would the whole man be identically the same. Therefore it is impossible for the separated soul to lose its sensitive powers.
Objection 7. Further, if the sensitive powers were to be corrupted when the body is corrupted, it would follow that they are weakened when the body is weakened. Yet this is not the case, for according to De Anima i, "if an old man were given the eye of a young man, he would, without doubt, see as well as a young man." Therefore neither are the sensitive powers corrupted when the body is corrupted.
On the contrary, Augustine says (De Eccl. Dogm. xix): "Of two substances alone does man consist, soul and body: the soul with its reason, and the body with its senses." Therefore the sensitive powers belong to the body: and consequently when the body is corrupted the sensitive powers remain not in the soul.
Further, the Philosopher, speaking of the separation of the soul, expresses himself thus (Metaph. xi, 3): "If, however, anything remain at last, we must ask what this is: because in certain subjects it is not impossible, for instance if the soul be of such a disposition, not the whole soul but the intellect; for as regards the whole soul this is probably impossible." Hence it seems that the whole soul is not separated from the body, but only the intellective powers of the soul, and consequently not the sensitive or vegetative powers.
Further, the Philosopher, speaking of the intellect, says (De Anima ii, 2): "This alone is ever separated, as the everlasting from the corruptible: for it is hereby clear that the remaining parts are not separable as some maintain." Therefore the sensitive powers do not remain in the separated soul.
I answer that, There are many opinions on this question. For some, holding the view that all the powers are in the soul in the same way as color is in a body, hold that the soul separated from the body takes all its powers away with it: because, if it lacked any one of them, it would follow that the soul is changed in its natural properties, since these cannot change so long as their subject remains. But the aforesaid view is false, for since a power is so called because it enables us to do or suffer something, and since to do and to be able belong to the same subject, it follows that the subject of a power is the same as that which is agent or patient. Hence the Philosopher says (De Somn. et Vigil.) that "where we find power there we find action." Now it is evident that certain operations, whereof the soul's powers are the principles, do not belong to the soul properly speaking but to the soul as united to the body, because they are not performed except through the medium of the body--such as to see, to hear, and so forth. Hence it follows that such like powers belong to the united soul and body as their subject, but to the soul as their quickening principle, just as the form is the principle of the properties of a composite being. Some operations, however, are performed by the soul without a bodily organ--for instance to understand, to consider, to will: wherefore, since these actions are proper to the soul, the powers that are the principles thereof belong to the soul not only as their principle but also as their subject. Therefore, since so long as the proper subject remains its proper passions must also remain, and when it is corrupted they also must be corrupted, it follows that these powers which use no bodily organ for their actions must needs remain in the separated body, while those which use a bodily organ must needs be corrupted when the body is corrupted: and such are all the powers belonging to the sensitive and the vegetative soul. On this account some draw a distinction in the sensitive powers of the soul: for they say that they are of two kinds--some being acts of organs and emanating from the soul into the body are corrupted with the body; others, whence the former originate, are in the soul, because by them the soul sensitizes the body for seeing, hearing, and so on; and these primary powers remain in the separated soul. But this statement seems unreasonable: because the soul, by its essence and not through the medium of certain other powers, is the origin of those powers which are the acts of organs, even as any form, from the very fact that by its essence it informs its matter, is the origin of the properties which result naturally in the composite. For were it necessary to suppose other powers in the soul, by means of which the powers that perfect the organs may flow from the essence of the soul, for the same reason it would be necessary to suppose other powers by means of which these mean powers flow from the essence of the soul, and so on to infinity, and if we have to stop it is better to do so at the first step.
Hence others say that the sensitive and other like powers do not remain in the separated soul except in a restricted sense, namely radically, in the same way as a result is in its principle: because there remains in the separated soul the ability to produce these powers if it should be reunited to the body; nor is it necessary for this ability to be anything in addition to the essence of the soul, as stated above. This opinion appears to be the more reasonable.
Reply to Objection 1. This saying of Augustine is to be understood as meaning that the soul takes away with it some of those powers actually, namely understanding and intelligence, and some radically, as stated above [Cf. I, 77, 8, ad 1 and infra 2, ad 1].
Reply to Objection 2. The senses which the soul takes away with it are not these external senses, but the internal, those, namely, which pertain to the intellective part, for the intellect is sometimes called sense, as Basil states in his commentary on the Proverbs, and again the Philosopher (Ethic. vi, 11). If, however, he means the external senses we must reply as above to the first objection.
Reply to Objection 3. As stated above, the sensitive powers are related to the soul, not as natural passions to their subject, but as compared to their origin: wherefore the conclusion does not follow.
Reply to Objection 4. The powers of the soul are not called its integral but its potential parts. Now the nature of such like wholes is that the entire energy of the whole is found perfectly in one of the parts, but partially in the others; thus in the soul the soul's energy is found perfectly in the intellective part, but partially in the others. Wherefore, as the powers of the intellective part remain in the separated soul, the latter will remain entire and undiminished, although the sensitive powers do not remain actually: as neither is the king's power decreased by the death of a mayor who shared his authority.
Reply to Objection 5. The body co-operates in merit, as an essential part of the man who merits. The sensitive powers, however, do not co-operate thus, since they are of the genus of accidents. Hence the comparison fails.
Reply to Objection 6. The powers of the sensitive soul are said to be acts of the organs, not as though they were the essential forms of those organs, except in reference to the soul whose powers they are. But they are the acts of the organs, by perfecting them for their proper operations, as heat is the act of fire by perfecting it for the purpose of heating. Wherefore, just as a fire would remain identically the same, although another individual heat were in it (even so the cold of water that has been heated returns not identically the same, although the water remains the same in identity), so the organs will be the same identically, although the powers be not identically the same.
Reply to Objection 7. The Philosopher is speaking there of these powers as being rooted in the soul. This is clear from his saying that "old age is an affection not of the soul, but of that in which the soul is," namely the body. For in this way the powers of the soul are neither weakened nor corrupted on account of the body.
Source: Summa Theologica (New Advent)