1 Objection 1: It would seem that there are not several powers of the soul. For the intellectual soul approaches nearest to the likeness of God. But in God there is one simple power: and therefore also in the intellectual soul.
1 Ad secundum sic proceditur. Videtur quod non sint plures potentiae animae. Anima enim intellectiva maxime ad divinam similitudinem accedit. Sed in Deo est una et simplex potentia. Ergo et in anima intellectiva.
2 Objection 2: Further, the higher a power is, the more unified it is. But the intellectual soul excels all other forms in power. Therefore above all others it has one virtue or power.
2 Praeterea, quanto virtus est superior, tanto est magis unita. Sed anima intellectiva excedit omnes alias formas in virtute. Ergo maxime debet habere unam virtutem seu potentiam.
3 Objection 3: Further, to operate belongs to what is in act. But by the one essence of the soul, man has actual existence in the different degrees of perfection, as we have seen above Question 76, Articles 3, 4). Therefore by the one power of the soul he performs operations of various degrees.
3 Praeterea, operari est existentis in actu. Sed per eandem essentiam animae homo habet esse secundum diversos gradus perfectionis, ut supra habitum est. Ergo per eandem potentiam animae operatur diversas operationes diversorum graduum.
4 On the contrary, The Philosopher places several powers in the soul De Anima ii, 2, 3).
4 Sed contra est quod philosophus, in II de anima ponit plures animae potentias.
5 I answer that, Of necessity we must place several powers in the soul. To make this evident, we observe that, as the Philosopher says De Coelo ii, 12), the lowest order of things cannot acquire perfect goodness, but they acquire a certain imperfect goodness, by few movements; and those which belong to a higher order acquire perfect goodness by many movements; and those yet higher acquire perfect goodness by few movements; and the highest perfection is found in those things which acquire perfect goodness without any movement whatever.
Thus he is least of all disposed of health, who can only acquire imperfect health by means of a few remedies; better disposed is he who can acquire perfect health by means of many remedies; and better still, he who can by few remedies; best of all is he who has perfect health without any remedies. We conclude, therefore, that things which are below man acquire a certain limited goodness; and so they have a few determinate operations and powers.
But man can acquire universal and perfect goodness, because he can acquire beatitude. Yet he is in the last degree, according to his nature, of those to whom beatitude is possible; therefore the human soul requires many and various operations and powers. But to angels a smaller variety of powers is sufficient. In God there is no power or action beyond His own Essence. There is yet another reason why the human soul abounds in a variety of powers, because it is on the confines of spiritual and corporeal creatures; and therefore the powers of both meet together in the soul.
5 Respondeo dicendum quod necesse est ponere plures animae potentias. Ad cuius evidentiam, considerandum est quod, sicut philosophus dicit in II de caelo, quae sunt in rebus infima, non possunt consequi perfectam bonitatem, sed aliquam imperfectam consequuntur paucis motibus; superiora vero his adipiscuntur perfectam bonitatem motibus multis; his autem superiora sunt quae adipiscuntur perfectam bonitatem motibus paucis; summa vero perfectio invenitur in his quae absque motu perfectam possident bonitatem. Sicut infime est ad sanitatem dispositus qui non potest perfectam consequi sanitatem, sed aliquam modicam consequitur paucis remediis; melius autem dispositus est qui potest perfectam consequi sanitatem, sed remediis multis; et adhuc melius, qui remediis paucis; optime autem, qui absque remedio perfectam sanitatem habet. Dicendum est ergo quod res quae sunt infra hominem, quaedam particularia bona consequuntur, et ideo quasdam paucas et determinatas operationes habent et virtutes. Homo autem potest consequi universalem et perfectam bonitatem, quia potest adipisci beatitudinem. Est tamen in ultimo gradu, secundum naturam, eorum quibus competit beatitudo, et ideo multis et diversis operationibus et virtutibus indiget anima humana. Angelis vero minor diversitas potentiarum competit. In Deo vero non est aliqua potentia vel actio, praeter eius essentiam. Est et alia ratio quare anima humana abundat diversitate potentiarum, videlicet quia est in confinio spiritualium et corporalium creaturarum, et ideo concurrunt in ipsa virtutes utrarumque creaturarum.
6 Reply to Objection 1: The intellectual soul approaches to the Divine likeness, more than inferior creatures, in being able to acquire perfect goodness; although by many and various means; and in this it falls short of more perfect creatures.
6 Ad primum ergo dicendum quod in hoc ipso magis ad similitudinem Dei accedit anima intellectiva quam creaturae inferiores, quod perfectam bonitatem consequi potest; licet per multa et diversa; in quo deficit a superioribus.
7 Reply to Objection 2: A unified power is superior if it extends to equal things: but a multiform power is superior to it, if it is over many things.
7 Ad secundum dicendum quod virtus unita est superior, si ad aequalia se extendat. Sed virtus multiplicata est superior, si plura ei subiiciantur.
8 Reply to Objection 3: One thing has one substantial existence, but may have several operations. So there is one essence of the soul, with several powers.
8 Ad tertium dicendum quod unius rei est unum esse substantiale, sed possunt esse operationes plures. Et ideo est una essentia animae, sed potentiae plures.