Objection 1. It would seem that temperance is not a special virtue. For Augustine says (De Morib. Eccl. xv) that "it belongs to temperance to preserve one's integrity and freedom from corruption for God's sake." But this is common to every virtue. Therefore temperance is not a special virtue.
Objection 2. Further, Ambrose says (De Offic. i, 42) that "what we observe and seek most in temperance is tranquillity of soul." But this is common to every virtue. Therefore temperance is not a special virtue.
Objection 3. Further, Tully says (De Offic. i, 27) that "we cannot separate the beautiful from the virtuous," and that "whatever is just is beautiful." Now the beautiful is considered as proper to temperance, according to the same authority (Tully, De Offic. i, 27). Therefore temperance is not a special virtue.
On the contrary, The Philosopher (Ethic. ii, 7; iii, 10) reckons it a special virtue.
I answer that, It is customary in human speech to employ a common term in a restricted sense in order to designate the principal things to which that common term is applicable: thus the word "city" is used antonomastically* to designate Rome. [Antonomasia is the figure of speech whereby we substitute the general for the individual term; e.g. The Philosopher for Aristotle]. Accordingly the word "temperance" has a twofold acceptation. First, in accordance with its common signification: and thus temperance is not a special but a general virtue, because the word "temperance" signifies a certain temperateness or moderation, which reason appoints to human operations and passions: and this is common to every moral virtue. Yet there is a logical difference between temperance and fortitude, even if we take them both as general virtues: since temperance withdraws man from things which seduce the appetite from obeying reason, while fortitude incites him to endure or withstand those things on account of which he forsakes the good of reason.
On the other hand, if we take temperance antonomastically, as withholding the appetite from those things which are most seductive to man, it is a special virtue, for thus it has, like fortitude, a special matter.
Reply to Objection 1. Man's appetite is corrupted chiefly by those things which seduce him into forsaking the rule of reason and Divine law. Wherefore integrity, which Augustine ascribes to temperance, can, like the latter, be taken in two ways: first, in a general sense, and secondly in a sense of excellence.
Reply to Objection 2. The things about which temperance is concerned have a most disturbing effect on the soul, for the reason that they are natural to man, as we shall state further on (A4,5). Hence tranquillity of soul is ascribed to temperance by way of excellence, although it is a common property of all the virtues.
Reply to Objection 3. Although beauty is becoming to every virtue, it is ascribed to temperance, by way of excellence, for two reasons. First, in respect of the generic notion of temperance, which consists in a certain moderate and fitting proportion, and this is what we understand by beauty, as attested by Dionysius (Div. Nom. iv). Secondly, because the things from which temperance withholds us, hold the lowest place in man, and are becoming to him by reason of his animal nature, as we shall state further on (A4,5; 142, 4), wherefore it is natural that such things should defile him. On consequence beauty is a foremost attribute of temperance which above all hinders man from being defiled. On like manner honesty [Honesty must be taken here in its broad sense as synonymous with moral goodness, from the point of view of decorum] is a special attribute of temperance: for Isidore says (Etym. x): "An honest man is one who has no defilement, for honesty means an honorable state." This is most applicable to temperance, which withstands the vices that bring most dishonor on man, as we shall state further on (142, 4).
Source: Summa Theologica (New Advent)