Objection 1. It would seem that there are not different moral virtues about different passions. For there is but one habit about things that concur in their source and end: as is evident especially in the case of sciences. But the passions all concur in one source, viz. love; and they all terminate in the same end, viz. joy or sorrow, as we stated above (25, A1,2,4; 27, 4). Therefore there is but one moral virtue about all the passions.
Objection 2. Further, if there were different moral virtues about different passions, it would follow that there are as many moral virtues as passions. But this clearly is not the case: since there is one moral virtue about contrary passions; namely, fortitude, about fear and daring; temperance, about pleasure and sorrow. Therefore there is no need for different moral virtues about different passions.
Objection 3. Further, love, desire, and pleasure are passions of different species, as stated above (Question 23, Article 4). Now there is but one virtue about all these three, viz. temperance. Therefore there are not different moral virtues about different passions.
On the contrary, Fortitude is about fear and daring; temperance about desire; meekness about anger; as stated in Ethic. iii, 6,10; iv, 5.
I answer that, It cannot be said that there is only one moral virtue about all the passions: since some passions are not in the same power as other passions; for some belong to the irascible, others to the concupiscible faculty, as stated above (Question 23, Article 1).
On the other hand, neither does every diversity of passions necessarily suffice for a diversity of moral virtues. First, because some passions are in contrary opposition to one another, such as joy and sorrow, fear and daring, and so on. About such passions as are thus in opposition to one another there must needs be one same virtue. Because, since moral virtue consists in a kind of mean, the mean in contrary passions stands in the same ratio to both, even as in the natural order there is but one mean between contraries, e.g. between black and white. Secondly, because there are different passions contradicting reason in the same manner, e.g. by impelling to that which is contrary to reason, or by withdrawing from that which is in accord with reason. Wherefore the different passions of the concupiscible faculty do not require different moral virtues, because their movements follow one another in a certain order, as being directed to the one same thing, viz. the attainment of some good or the avoidance of some evil: thus from love proceeds desire, and from desire we arrive at pleasure; and it is the same with the opposite passions, for hatred leads to avoidance or dislike, and this leads to sorrow. On the other hand, the irascible passions are not all of one order, but are directed to different things: for daring and fear are about some great danger; hope and despair are about some difficult good; while anger seeks to overcome something contrary which has wrought harm. Consequently there are different virtues about such like passions: e.g. temperance, about the concupiscible passions; fortitude, about fear and daring; magnanimity, about hope and despair; meekness, about anger.
Reply to Objection 1. All the passions concur in one common principle and end; but not in one proper principle or end: and so this does not suffice for the unity of moral virtue.
Reply to Objection 2. Just as in the natural order the same principle causes movement from one extreme and movement towards the other; and as in the intellectual order contraries have one common ratio; so too between contrary passions there is but one moral virtue, which, like a second nature, consents to reason's dictates.
Reply to Objection 3. Those three passions are directed to the same object in a certain order, as stated above: and so they belong to the same virtue.
Source: Summa Theologica (New Advent)