To the second one proceeds thus. It seems that it is unfitting to distinguish three speculative intellectual virtues, to wit, wisdom, knowledge, and intellection. For species ought not to be divided into genera, but wisdom is a sort of knowledge, as is said in Ethic. VI. Therefore wisdom ought not to be divided from knowledge in the numbering of intellectual virtues.
Further, in the division of powers, habitudes, and acts, which is considered according to objects, one considers principally the distinction that is according to the formal notion of the objects, as is obvious from what was said above. Therefore different habitudes ought not to be distinguished according to the material object, but according to the formal notion of that object. But the source of demonstration is the notion for knowing conclusions. Therefore intellection of the sources ought not to be put in another habitude, or another virtue, from knowledge of the conclusions.
Further, intellectual virtue is said of that which is in the rational itself through essence. But reason, even speculative, as it reasons by deducing demonstratively, so also it reasons by deducing dialectically. Therefore knowledge, which is caused by demonstrative deduction, is put forward as a speculative intellectual virtue -- and so also opinion.
But contrariwise is that the Philosopher, Ethic. VI, puts forward only these three speculative intellectual virtues, to wit, wisdom, knowledge, and intellection.
I reply that it must be said that, as was already said, speculative intellectual virtue is that through which speculative intellect is completed so as to consider the true, for this is its good work. Now the true can be considered in two ways: in one way, as recognized through itself [per se notum]; in another way, as recognized through another.
(1) Now what is recognized through itself has itself as a source, and is perceived immediately by the intellect. And thus the habitude completing the intellect to this kind of consideration of the true, is called intellection, which is the habitude of the sources.
(2) But the true that is recognized through another is not perceived immediately by the intellect, but through inquiry of reason, and has itself in the notion of an endpoint. This is able to be in two ways: in one way, as being the ultimate in some genus; in another way, as being the ultimate with respect to the whole of human cognition. And because those things that are recognized afterward with respect to us, are beforehand and more recognized according to their nature, as is said in Phys. I, therefore that which is ultimate with respect to the whole of human cognition is that which is primarily and maximally cognizable according to nature. And concerning this kind is wisdom, which considers the highest causes, as is said in Metaphys. I. Thus fittingly it judges and sets in order all things, because complete and universal judgment cannot be had without resolution to first causes.
(3) But as to that which is ultimate in this or that genus of cognizables, knowledge completes the intellect. And therefore according to the different genera of knowables, there are diverse habitudes of knowledge, whereas wisdom is only one.
To the first, therefore, it must be said that wisdom is a sort of knowledge inasmuch as it has that which is common to all forms of knowledge, namely, that it demonstrates conclusions from sources. But because it has something proper to it above other forms of knowledge, to with, that it judges all things, and not only as to conclusions but also as to first sources, therefore it has the notion of a more complete virtue than knowledge.
To the second it must be said that when the notion of an object under one act is referred to power or habitude, then powers or habitudes are not distinguished according to the notion of the object and the material object, just as to the same visual power pertains seeing color and light, which is the notion for seeing color and seen together with it. But the sources of demonstration are able to be considered on their own, without considering conclusions. They are also able to be considered along with conclusions, insofar as the sources are drawn out [deducuntur] into conclusions. Therefore to consider the sources in this second way pertains to knowledge, which also considers conclusions, but to consider the sources in themselves pertains to intellection. Thus, if one rightly considers, these three virtues are not distinguished from each other equally but in a sort of ordering, as happens in all powers for which one part is more complete than another, as the rational soul is more complete than the sensory, and the sensory than the vegetative. For in this way, knowledge depends on intellection as more sourceward. And both depend on wisdom as most sourceward, which contains under itself both intellection and knowledge, as judging the conclusions of forms of knowledge and their sources.
To the third it must be said that, as was said above, the habitude of virtue has itself determinately to good, but not in any way to bad. But the good of the intellect is the true, and its bad is the false. Thus only those habitudes are called intellectual virtues to which the true is always ascribed, and never the false. But opinion and suspicion are able to be true and false. And therefore they are not intellectual virtues, as is said in Ethic. VI.
[Thomas Aquinas, ST 2-1.57.2, my rough translation. The Latin is here, the Dominican Fathers translation is here.]
This is one of those articles that is trickier to translate straightforwardly than it looks. (It's notable that the Dominican Fathers translation is fairly paraphrastic in parts.) Ratio gets a full workout here; it can mean 'reason, notion, nature, ground, formal aspect', and a colloquial translation would almost have to use the full gamut. The fact that principium (principle) literally means 'source' or 'beginning' plays an essential, load-bearing role in the argument. The idiomatic phrase, se habet, closely associated with habitudes, returns, and not in an incidental way; I've just translated it literally as 'has itself', but it always indicates disposition, relation, orientation. (Perhaps 'holds itself' would be a reasonably close English idiom for it: in habitude, a power holds itself toward an object, so that virtue, for instance, holds itself in its termination to good.) The fact that intellectus is the name of both the power and one of its virtues also seems to be doing some work. A small but interesting point is that to describe what we call 'deduction', the medievals generally used 'syllogismus' -- as is found here in the third objection -- but in the reply to the first objection, St. Thomas uses the root verb of 'deduction' as a metaphor to describe what is done in this kind of reasoning.
The argument here is interesting, and captures something that is perhaps often lost in discussing Aquinas on the intellectual virtues, namely, that we in some sense start in medias res. Understanding or intellection (intellectus) concerns principles known per se; with those starting points, we ascend to more fundamental first principles in wisdom (sapientia) and descend to derivative conclusions in knowledge (scientia), going both directions by reasoning. Thus sapientia is very much like scientia, in that they both do not deal with what we recognize immediately, but sapientia is higher even than intellectus, on which scientia depends. We do not start at the top, with what is most fundamental in itself, but with what is most fundamental to minds like ours. I think a common temptation is to think that wisdom is somehow beyond reasoning, a direct insight into things; such a temptation collapses sapientia into intellectus, whereas St. Thomas insists that what wisdom concerns itself with has to be reached and not just perceived.
