1 Objection 1: It would seem that our intellect knows the habits of the soul by their essence. For Augustine says De Trin. xiii, 1): Faith is not seen in the heart wherein it abides, as the soul of a man may be seen by another from the movement of the body; but we know most certainly that it is there, and conscience proclaims its existence; and the same principle applies to the other habits of the soul. Therefore the habits of the soul are not known by their acts, but by themselves.
1 Ad secundum sic proceditur. Videtur quod intellectus noster cognoscat habitus animae per essentiam eorum. Dicit enim Augustinus, XIII de Trin., non sic videtur fides in corde in quo est, sicut anima alterius hominis ex motibus corporis videtur; sed eam tenet certissima scientia, clamatque conscientia. Et eadem ratio est de aliis habitibus animae. Ergo habitus animae non cognoscuntur per actus, sed per seipsos.
2 Objection 2: Further, material things outside the soul are known by their likeness being present in the soul, and are said therefore to be known by their likenesses. But the soul's habits are present by their essence in the soul. Therefore the habits of the soul are known by their essence.
2 Praeterea, res materiales, quae sunt extra animam, cognoscuntur per hoc quod similitudines earum sunt praesentialiter in anima; et ideo dicuntur per suas similitudines cognosci. Sed habitus animae praesentialiter per suam essentiam sunt in anima. Ergo per suam essentiam cognoscuntur.
3 Objection 3: Further, whatever is the cause of a thing being such is still more so. But habits and intelligible species cause things to be known by the soul. Therefore they are still more known by the soul in themselves.
3 Praeterea, propter quod unumquodque tale, et illud magis. Sed res aliae cognoscuntur ab anima propter habitus et species intelligibiles. Ergo ista magis per seipsa ab anima cognoscuntur.
4 On the contrary, Habits like powers are the principles of acts. But as is said De Anima ii, 4), acts and operations are logically prior to powers. Therefore in the same way they are prior to habits; and thus habits, like the powers, are known by their acts.
4 Sed contra, habitus sunt principia actuum, sicut et potentiae. Sed sicut dicitur II de anima, priores potentiis, secundum rationem, actus et operationes sunt. Ergo eadem ratione sunt priores habitibus. Et ita habitus per actus cognoscuntur, sicut et potentiae.
5 I answer that, A habit is a kind of medium between mere power and mere act. Now, it has been said Article 1) that nothing is known but as it is actual: therefore so far as a habit fails in being a perfect act, it falls short in being of itself knowable, and can be known only by its act; thus, for example, anyone knows he has a habit from the fact that he can produce the act proper to that habit; or he may inquire into the nature and idea of the habit by considering the act. The first kind of knowledge of the habit arises from its being present, for the very fact of its presence causes the act whereby it is known. The second kind of knowledge of the habit arises from a careful inquiry, as is explained above of the mind Article 1).
5 Respondeo dicendum quod habitus quodammodo est medium inter potentiam puram et purum actum. Iam autem dictum est quod nihil cognoscitur nisi secundum quod est actu. Sic ergo inquantum habitus deficit ab actu perfecto, deficit ab hoc, ut non sit per seipsum cognoscibilis, sed necesse est quod per actum suum cognoscatur, sive dum aliquis percipit se habere habitum, per hoc quod percipit se producere actum proprium habitus; sive dum aliquis inquirit naturam et rationem habitus, ex consideratione actus. Et prima quidem cognitio habitus fit per ipsam praesentiam habitus, quia ex hoc ipso quod est praesens, actum causat, in quo statim percipitur. Secunda autem cognitio habitus fit per studiosam inquisitionem, sicut supra dictum est de mente.
6 Reply to Objection 1: Although faith is not known by external movement of the body, it is perceived by the subject wherein it resides, by the interior act of the heart. For no one knows that he has faith unless he knows that he believes.
6 Ad primum ergo dicendum quod, etsi fides non cognoscatur per exteriores corporis motus, percipitur tamen etiam ab eo in quo est, per interiorem actum cordis. Nullus enim fidem se habere scit, nisi per hoc quod se credere percipit.
7 Reply to Objection 2: Habits are present in our intellect, not as its object since, in the present state of life, our intellect's object is the nature of a material thing as stated above Question 84, Article 7), but as that by which it understands.
7 Ad secundum dicendum quod habitus sunt praesentes in intellectu nostro, non sicut obiecta intellectus quia obiectum intellectus nostri, secundum statum praesentis vitae, est natura rei materialis, ut supra dictum est); sed sunt praesentes in intellectu ut quibus intellectus intelligit.
8 Reply to Objection 3: The axiom, whatever is the cause of a thing being such, is still more so, is true of things that are of the same order, for instance, of the same kind of cause; for example, we may say that health is desirable on account of life, and therefore life is more desirable still. But if we take things of different orders the axiom is not true: for we may say that health is caused by medicine, but it does not follow that medicine is more desirable than health, for health belongs to the order of final causes, whereas medicine belongs to the order of efficient causes. So of two things belonging essentially to the order of the objects of knowledge, the one which is the cause of the other being known, is the more known, as principles are more known than conclusions. But habit as such does not belong to the order of objects of knowledge; nor are things known on account of the habit, as on account of an object known, but as on account of a disposition or form whereby the subject knows: and therefore the argument does not prove.
8 Ad tertium dicendum quod, cum dicitur, propter quod unumquodque, illud magis, veritatem habet, si intelligatur in his quae sunt unius ordinis, puta in uno genere causae, puta si dicatur quod sanitas est propter vitam, sequitur quod vita sit magis desiderabilis. Si autem accipiantur ea quae sunt diversorum ordinum, non habet veritatem, ut si dicatur quod sanitas est propter medicinam, non ideo sequitur quod medicina sit magis desiderabilis, quia sanitas est in ordine finium, medicina autem in ordine causarum efficientium. Sic igitur si accipiamus duo, quorum utrumque sit per se in ordine obiectorum cognitionis; illud propter quod aliud cognoscitur, erit magis notum, sicut principia conclusionibus. Sed habitus non est de ordine obiectorum, inquantum est habitus; nec propter habitum aliqua cognoscuntur sicut propter obiectum cognitum, sed sicut propter dispositionem vel formam qua cognoscens cognoscit, et ideo ratio non sequitur.