1 Objection 1: It would seem that the speculative and practical intellects are distinct powers. For the apprehensive and motive are different kinds of powers, as is clear from De Anima ii, 3. But the speculative intellect is merely an apprehensive power; while the practical intellect is a motive power. Therefore they are distinct powers.
1 Ad undecimum sic proceditur. Videtur quod intellectus speculativus et practicus sint diversae potentiae. Apprehensivum enim et motivum sunt diversa genera potentiarum, ut patet in II de anima. Sed intellectus speculativus est apprehensivus tantum, intellectus autem practicus est motivus. Ergo sunt diversae potentiae.
2 Objection 2: Further, the different nature of the object differentiates the power. But the object of the speculative intellect is truth, and of the practical is good; which differ in nature. Therefore the speculative and practical intellect are distinct powers.
2 Praeterea, diversa ratio obiecti diversificat potentiam. Sed obiectum speculativi intellectus est verum, practici autem bonum; quae differunt ratione. Ergo intellectus speculativus et practicus sunt diversae potentiae.
3 Objection 3: Further, in the intellectual part, the practical intellect is compared to the speculative, as the estimative is to the imaginative power in the sensitive part. But the estimative differs from the imaginative, as power form power, as we have said above Question 78, Article 4). Therefore also the speculative intellect differs from the practical.
3 Praeterea, in parte intellectiva intellectus practicus comparatur ad speculativum, sicut aestimativa ad imaginativam in parte sensitiva. Sed aestimativa differt ab imaginativa sicut potentia a potentia, ut supra dictum est. Ergo et intellectus practicus a speculativo.
4 On the contrary, The speculative intellect by extension becomes practical De Anima iii, 10). But one power is not changed into another. Therefore the speculative and practical intellects are not distinct powers.
4 Sed contra est quod dicitur in III de anima, quod intellectus speculativus per extensionem fit practicus. Una autem potentia non mutatur in aliam. Ergo intellectus speculativus et practicus non sunt diversae potentiae.
5 I answer that, The speculative and practical intellects are not distinct powers. The reason of which is that, as we have said above Question 77, Article 3), what is accidental to the nature of the object of a power, does not differentiate that power; for it is accidental to a thing colored to be man, or to be great or small; hence all such things are apprehended by the same power of sight. Now, to a thing apprehended by the intellect, it is accidental whether it be directed to operation or not, and according to this the speculative and practical intellects differ. For it is the speculative intellect which directs what it apprehends, not to operation, but to the consideration of truth; while the practical intellect is that which directs what it apprehends to operation. And this is what the Philosopher says De Anima iii, 10); that the speculative differs from the practical in its end. Whence each is named from its end: the one speculative, the other practical, that is, operative.
5 Respondeo dicendum quod intellectus practicus et speculativus non sunt diversae potentiae. Cuius ratio est quia, ut supra dictum est, id quod accidentaliter se habet ad obiecti rationem quam respicit aliqua potentia, non diversificat potentiam, accidit enim colorato quod sit homo, aut magnum aut parvum; unde omnia huiusmodi eadem visiva potentia apprehenduntur. Accidit autem alicui apprehenso per intellectum, quod ordinetur ad opus, vel non ordinetur. Secundum hoc autem differunt intellectus speculativus et practicus. Nam intellectus speculativus est, qui quod apprehendit, non ordinat ad opus, sed ad solam veritatis considerationem, practicus vero intellectus dicitur, qui hoc quod apprehendit, ordinat ad opus. Et hoc est quod philosophus dicit in III de anima, quod speculativus differt a practico, fine. Unde et a fine denominatur uterque, hic quidem speculativus, ille vero practicus, idest operativus.
6 Reply to Objection 1: The practical intellect is a motive power, not as executing movement, but as directing towards it; and this belongs to it according to its mode of apprehension.
6 Ad primum ergo dicendum quod intellectus practicus est motivus, non quasi exequens motum, sed quasi dirigens ad motum. Quod convenit ei secundum modum suae apprehensionis.
7 Reply to Objection 2: Truth and good include one another; for truth is something good, otherwise it would not be desirable; and good is something true, otherwise it would not be intelligible. Therefore as the object of the appetite may be something true, as having the aspect of good, for example, when some one desires to know the truth; so the object of the practical intellect is good directed to the operation, and under the aspect of truth. For the practical intellect knows truth, just as the speculative, but it directs the known truth to operation.
7 Ad secundum dicendum quod verum et bonum se invicem includunt, nam verum est quoddam bonum, alioquin non esset appetibile; et bonum est quoddam verum, alioquin non esset intelligibile. Sicut igitur obiectum appetitus potest esse verum, inquantum habet rationem boni, sicut cum aliquis appetit veritatem cognoscere; ita obiectum intellectus practici est bonum ordinabile ad opus, sub ratione veri. Intellectus enim practicus veritatem cognoscit, sicut et speculativus; sed veritatem cognitam ordinat ad opus.
8 Reply to Objection 3: Many differences differentiate the sensitive powers, which do not differentiate the intellectual powers, as we have said above Article 7, ad 2; Question 77, Article 3, ad 4).
8 Ad tertium dicendum quod multae differentiae diversificant sensitivas potentias, quae non diversificant potentias intellectivas, ut supra dictum est.