To the third one proceeds thus. It seems that human virtue is not sufficiently divided according to moral and intellectual virtue. For prudence seems to be some mean between moral and intellectual virtue, since it is enumerated with intellectual virtue in Ethic. VI, and also is commonly enumerated by all among the four cardinal virtues, which are moral, as will be obvious below. Therefore virtue is not sufficiently divided according to moral and intellectual as immediate.
Further, continence and perseverance and patience are not reckoned among intellectual virtues. Nor are they moral virtues, because they do not have a passional mean, but passions abound in them. Therefore virtue is not sufficiently divided according to intellectual and moral.
Further, faith, hope, and charity are sorts of virtue. But they are not intellectual virtues, for these are only five, to wit, knowledge, wisdom, intellection, prudence, and craft, as was said. Nor are they moral virtues because they are not about passions, which moral virtues are chiefly about. Therefore virtue is not sufficiently divided according to intellectual and moral.
But contrariwise, the Philosopher says in Ethic. II that virtue is twofold, the one intellectual and the other moral.
I reply that it must be said that virtue is a sort of habitude completing a human being for working well. Now the source [principium] of human action is only twofold, to wit, intellect or reason and striving, for these are the two movers [moventia] in the human being, as is said in De Anima III. Thus any human virtue should be the completing of one of these sources. If, therefore, it is a completing of speculative or practical intellect for good human action, it will be intellectual virtue, but if it is a completing of the striving part, it will be moral virtue. Thus by elimination [relinquitur quod] every human virtue is either intellectual or moral.
To the first it must be said that prudence according to its essence is intellectual virtue, but according to its matter it converges on [convenit cum] the moral virtues, for it is right reason for enactables, as was said above. And according to this it is enumerated with the moral virtues.
To the second it must be said that continence and perseverance are not completions of the sense-relevant striving power. This is obvious in the fact that, in the continent and persevering, passions super-abound in them, which would not be if sense-relevant striving were completed by some habitude conforming it to reason. Now containing, or persevering, is a completion of the rational part, which holds itself against passions lest it be drawn off. But it falls short of the notion of virtue, for intellectual virtue that has itself [se habere] well about morals presupposes right striving for the end, so that it has itself [se habeat] rightly about sources, that is, ends from which we reason, which is lacking from continence and perseverance. Nor can there be complete working proceeding from two powers unless each power is completed by due habitude, just as the complete action does not follow from one acting instrumentally if the instrument is not well disposed, however complete the principal agent may be. Thus if sense-relevant striving that is moved by the rational part is not complete, then however complete the rational part, the following action will not be complete. So neither will the source of the action be virtue. And because of this, continence from delights and perservance from sorrows are not virtues, but are something lesser than virtue, as the Philosopher says in Ethic. VII.
To the third it must be said that faith, hope, and charity are above human virtues, for they are virtues of a human being so far as he is made participant of divine grace.
[St. Thomas Aquinas, ST 2-1.58.3, my translation. The Dominican Fathers translation is here, the Latin is here.]
Sufficio is the verb for supplying or providing, so 'sufficiently divides' means that the division, taken together as a division (without overlapping) supplies the whole.
Note that this article doesn't just divide human virtues into intellectual virtues and moral virtues, but also relates them to what is immediately below them (reply to objection 2) and what is directly above them (reply to objection 3). It also deals with the most obvious puzzle case for taking the division to be a strict division, namely, prudence, which seems to fall on both sides; in fact, prudence is an intellectual virtue, but it is the intellectual virtue about the whole field of what moral virtues are about, so it is counted as a moral virtue.