Thomas Aquinas

“ Consequently there is nothing to prevent many superficially different habits from being in one power.
Reply to Objection 3: A body is informed by its shape as by its own terminal boundaries: whereas a habit is not the terminal boundary of a power, but the disposition of a power to an act as to its ultimate term. Consequently one same power cannot have several acts at the same time, except in so far as perchance one act is comprised in another; just as neither can a body have several shapes, save in so far as one shape enters into another, as a three-sided in a four-sided figure. ”

“ For a habit does not extend to many things save in relation to one, whence it derives its unity.
Reply to Objection 1: That a habit is engendered little by little, is due, not to one part being engendered after another, but to the fact that the subject does not acquire all at once a firm and difficultly changeable disposition; and also to the fact that it begins by being imperfectly in the subject, and is gradually perfected. The same applies to other qualities.
Reply to Objection 2: The parts which are assigned to each cardinal virtue, are not integral parts that combine to form a whole ”

“ But since this multiplicity is directed to one thing, on which the habit is chiefly intent, hence it is that a habit is a simple quality, not composed to several habits, even though it extend to many things. ”

“ Objection 2: Further, a whole is made up of its parts. Now many parts are assigned to one habit: thus Tully assigns many parts of fortitude, temperance, and other virtues. Therefore one habit is made up of many. ”

“ Wherefore, just as several objects can move one passive power, so can one passive power be the subject of several acts or perfections specifically diverse. Now habits are qualities or forms adhering to a power, and inclining that power to acts of a determinate species. Consequently several habits, even as several specifically different acts, can belong to one power.
Reply to Objection 1: Even as in natural things, diversity of species is according to the form, and diversity of genus, according to matter, as stated in Metaph. ”