1 Objection 1: It would seem that the powers of the soul are not distinguished by acts and objects. For nothing is determined to its species by what is subsequent and extrinsic to it. But the act is subsequent to the power; and the object is extrinsic to it. Therefore the soul's powers are not specifically distinct by acts and objects.
1 Ad tertium sic proceditur. Videtur quod potentiae non distinguantur per actus et obiecta. Nihil enim determinatur ad speciem per illud quod posterius, vel extrinsecum est. Actus autem est posterior potentia; obiectum autem est extrinsecum. Ergo per ea potentiae non distinguuntur secundum speciem.
2 Objection 2: Further, contraries are what differ most from each other. Therefore if the powers are distinguished by their objects, it follows that the same power could not have contrary objects. This is clearly false in almost all the powers; for the power of vision extends to white and black, and the power to taste to sweet and bitter.
2 Praeterea, contraria sunt quae maxime differunt. Si igitur potentiae distinguerentur penes obiecta, sequeretur quod contrariorum non esset eadem potentia. Quod patet esse falsum fere in omnibus, nam potentia visiva eadem est albi et nigri, et gustus idem est dulcis et amari.
3 Objection 3: Further, if the cause be removed, the effect is removed. Hence if the difference of powers came from the difference of objects, the same object would not come under different powers. This is clearly false; for the same thing is known by the cognitive power, and desired by the appetitive.
3 Praeterea, remota causa, removetur effectus. Si igitur potentiarum differentia esset ex differentia obiectorum, idem obiectum non pertineret ad diversas potentias. Quod patet esse falsum, nam idem est quod potentia cognoscitiva cognoscit, et appetitiva appetit.
4 Objection 4: Further, that which of itself is the cause of anything, is the cause thereof, wherever it is. But various objects which belong to various powers, belong also to some one power; as sound and color belong to sight and hearing, which are different powers, yet they come under the one power of common sense. Therefore the powers are not distinguished according to the difference of their objects.
4 Praeterea, id quod per se est causa alicuius, in omnibus causat illud. Sed quaedam obiecta diversa, quae pertinent ad diversas potentias, pertinent etiam ad aliquam unam potentiam, sicut sonus et color pertinent ad visum et auditum, quae sunt diversae potentiae; et tamen pertinent ad unam potentiam sensus communis. Non ergo potentiae distinguuntur secundum differentiam obiectorum.
5 On the contrary, Things that are subsequent are distinguished by what precedes. But the Philosopher says De Anima ii, 4) that acts and operations precede the powers according to reason; and these again are preceded by their opposites, that is their objects. Therefore the powers are distinguished according to their acts and objects.
5 Sed contra, posteriora distinguuntur secundum priora. Sed philosophus dicit II de anima, quod priores potentiis actus et operationes secundum rationem sunt; et adhuc his priora sunt opposita, sive obiecta. Ergo potentiae distinguuntur secundum actus et obiecta.
6 I answer that, A power as such is directed to an act. Wherefore we seek to know the nature of a power from the act to which it is directed, and consequently the nature of a power is diversified, as the nature of the act is diversified. Now the nature of an act is diversified according to the various natures of the objects. For every act is either of an active power or of a passive power. Now, the object is to the act of a passive power, as the principle and moving cause: for color is the principle of vision, inasmuch as it moves the sight.
On the other hand, to the act of an active power the object is a term and end; as the object of the power of growth is perfect quantity, which is the end of growth. Now, from these two things an act receives its species, namely, from its principle, or from its end or term; for the act of heating differs from the act of cooling, in this, that the former proceeds from something hot, which is the active principle, to heat; the latter from something cold, which is the active principle, to cold.
Therefore the powers are of necessity distinguished by their acts and objects. Nevertheless, we must observe that things which are accidental do not change the species. For since to be colored is accidental to an animal, its species is not changed by a difference of color, but by a difference in that which belongs to the nature of an animal, that is to say, by a difference in the sensitive soul, which is sometimes rational, and sometimes otherwise. Hence rational and irrational are differences dividing animal, constituting its various species.
In like manner therefore, not any variety of objects diversifies the powers of the soul, but a difference in that to which the power of its very nature is directed. Thus the senses of their very nature are directed to the passive quality which of itself is divided into color, sound, and the like, and therefore there is one sensitive power with regard to color, namely, the sight, and another with regard to sound, namely, hearing. But it is accidental to a passive quality, for instance, to something colored, to be a musician or a grammarian, great or small, a man or a stone. Therefore by reason of such differences the powers of the soul are not distinct.
6 Respondeo dicendum quod potentia, secundum illud quod est potentia, ordinatur ad actum. Unde oportet rationem potentiae accipi ex actu ad quem ordinatur, et per consequens oportet quod ratio potentiae diversificetur, ut diversificatur ratio actus. Ratio autem actus diversificatur secundum diversam rationem obiecti. Omnis enim actio vel est potentiae activae, vel passivae. Obiectum autem comparatur ad actum potentiae passivae, sicut principium et causa movens, color enim inquantum movet visum, est principium visionis. Ad actum autem potentiae activae comparatur obiectum ut terminus et finis, sicut augmentativae virtutis obiectum est quantum perfectum, quod est finis augmenti.
Ex his autem duobus actio speciem recipit, scilicet ex principio, vel ex fine seu termino, differt enim calefactio ab infrigidatione, secundum quod haec quidem a calido, scilicet activo, ad calidum; illa autem a frigido ad frigidum procedit. Unde necesse est quod potentiae diversificentur secundum actus et obiecta. Sed tamen considerandum est quod ea quae sunt per accidens, non diversificant speciem. Quia enim coloratum accidit animali, non diversificantur species animalis per differentiam coloris, sed per differentiam eius quod per se accidit animali, per differentiam scilicet animae sensitivae, quae quandoque invenitur cum ratione, quandoque sine ratione.
Unde rationale et irrationale sunt differentiae divisivae animalis, diversas eius species constituentes. Sic igitur non quaecumque diversitas obiectorum diversificat potentias animae; sed differentia eius ad quod per se potentia respicit. Sicut sensus per se respicit passibilem qualitatem, quae per se dividitur in colorem, sonum et huiusmodi, et ideo alia potentia sensitiva est coloris, scilicet visus, et alia soni, scilicet auditus. Sed passibili qualitati, ut colorato accidit esse musicum vel grammaticum, vel magnum et parvum, aut hominem vel lapidem. Et ideo penes huiusmodi differentias potentiae animae non distinguuntur.
7 Reply to Objection 1: Act, though subsequent in existence to power, is, nevertheless, prior to it in intention and logically; as the end is with regard to the agent. And the object, although extrinsic, is, nevertheless, the principle or end of the action; and those conditions which are intrinsic to a thing, are proportionate to its principle and end.
7 Ad primum ergo dicendum quod actus, licet sit posterior potentia in esse, est tamen prior in intentione et secundum rationem, sicut finis agente. Obiectum autem, licet sit extrinsecum, est tamen principium vel finis actionis. Principio autem et fini proportionantur ea quae sunt intrinseca rei.
8 Reply to Objection 2: If any power were to have one of two contraries as such for its object, the other contrary would belong to another power. But the power of the soul does not regard the nature of the contrary as such, but rather the common aspect of both contraries; as sight does not regard white as such, but as color. This is because of two contraries one, in a manner, includes the idea of the other, since they are to one another as perfect and imperfect.
8 Ad secundum dicendum quod, si potentia aliqua per se respiceret unum contrariorum sicut obiectum, oporteret quod contrarium ad aliam potentiam pertineret. Sed potentia animae non per se respicit propriam rationem contrarii, sed communem rationem utriusque contrariorum, sicut visus non respicit per se rationem albi, sed rationem coloris. Et hoc ideo, quia unum contrariorum est quodammodo ratio alterius, cum se habeant sicut perfectum et imperfectum.
9 Reply to Objection 3: Nothing prevents things which coincide in subject, from being considered under different aspects; therefore they can belong to various powers of the soul.
9 Ad tertium dicendum quod nihil prohibet id quod est subiecto idem esse diversum secundum rationem. Et ideo potest ad diversas potentias animae pertinere.
10 Reply to Objection 4: The higher power of itself regards a more universal formality of the object than the lower power; because the higher a power is, to a greater number of things does it extend. Therefore many things are combined in the one formality of the object, which the higher power considers of itself; while they differ in the formalities regarded by the lower powers of themselves. Thus it is that various objects belong to various lower powers; which objects, however, are subject to one higher power.
10 Ad quartum dicendum quod potentia superior per se respicit universaliorem rationem obiecti, quam potentia inferior, quia quanto potentia est superior, tanto ad plura se extendit. Et ideo multa conveniunt in una ratione obiecti, quam per se respicit superior potentia, quae tamen differunt secundum rationes quas per se respiciunt inferiores potentiae. Et inde est quod diversa obiecta pertinent ad diversas inferiores potentias, quae tamen uni superiori potentiae subduntur.