I answer that, As stated above (A. 3), these four virtues are understood differently by various writers.  For some take them as signifying certain general conditions of the human mind, to be found in all the virtues:  so that, to wit, prudence is merely a certain rectitude of discretion in any actions or matters whatever; justice, a certain rectitude of the mind, whereby a man does what he ought in any matters; temperance, a disposition of the mind, moderating any passions or operations, so as to keep them within bounds; and fortitude, a disposition whereby the soul is strengthened for that which is in accord with reason, against any assaults of the passions, or the toil involved by any operations.  To distinguish these four virtues in this way does not imply that justice, temperance and fortitude are distinct virtuous habits:  because it is fitting that every moral virtue, from the fact that it is a habit, should be accompanied by a certain firmness so as not to be moved by its contrary:  and this, we have said, belongs to fortitude.  Moreover, inasmuch as it is a virtue, it is directed to good which involves the notion of right and due; and this, we have said, belongs to justice.  Again, owing to the fact that it is a moral virtue partaking of reason, it observes the mode of reason in all things, and does not exceed its bounds, which has been stated to belong to temperance.  It is only in the point of having discretion, which we ascribed to prudence, that there seems to be a distinction from the other three, inasmuch as discretion belongs essentially to reason; whereas the other three imply a certain share of reason by way of a kind of application (of reason) to passions or operations.  According to the above explanation, then, prudence would be distinct from the other three virtues:  but these would not be distinct from one another; for it is evident that one and the same virtue is both habit, and virtue, and moral virtue.

Others, however, with better reason, take these four virtues, according as they have their special determinate matter; each of its own matter, in which special commendation is given to that general condition from which the virtue’s name is taken as stated above (A. 3).  In this way it is clear that the aforesaid virtues are distinct habits, differentiated in respect of their diverse objects.

Reply Obj. 1:  Gregory is speaking of these four virtues in the first sense given above.  It may also be said that these four virtues qualify one another by a kind of overflow.  For the qualities of prudence overflow on to the other virtues in so far as they are directed by prudence.  And each of the others overflows on to the rest, for the reason that whoever can do what is harder, can do what is less difficult.  Wherefore whoever can curb his desires for the pleasures of touch, so that they keep within bounds, which is a very hard thing to do, for this very reason is more able to check his daring in dangers of death, so as