Objection 1. It would seem that no virtue regards the outward movements of the body. For every virtue pertains to the spiritual beauty of the soul, according to Psalm 44:14, "All the glory of the king's daughter is within," and a gloss adds, "namely, in the conscience." Now the movements of the body are not within, but without. Therefore there can be no virtue about them.
Objection 2. Further, "Virtues are not in us by nature," as the Philosopher states (Ethic. ii, 1). But outward bodily movements are in man by nature, since it is by nature that some are quick, and some slow of movement, and the same applies to other differences of outward movements. Therefore there is no virtue about movements of this kind.
Objection 3. Further, every moral virtue is either about actions directed to another person, as justice, or about passions, as temperance and fortitude. Now outward bodily movements are not directed to another person, nor are they passions. Therefore no virtue is connected with them.
Objection 4. Further, study should be applied to all works of virtue, as stated above (166, 1, Objection 1; 2, ad 1). Now it is censurable to apply study to the ordering of one's outward movements: for Ambrose says (De Offic. i, 18): "A becoming gait is one that reflects the carriage of authority, has the tread of gravity, and the foot-print of tranquillity: yet so that there be neither study nor affectation, but natural and artless movement." Therefore seemingly there is no virtue about the style of outward movements.
On the contrary, The beauty of honesty [Cf. 145, 1] pertains to virtue. Now the style of outward movements pertains to the beauty of honesty. For Ambrose says (De Offic. i, 18): "The sound of the voice and the gesture of the body are distasteful to me, whether they be unduly soft and nerveless, or coarse and boorish. Let nature be our model; her reflection is gracefulness of conduct and beauty of honesty." Therefore there is a virtue about the style of outward movement.
I answer that, Moral virtue consists in the things pertaining to man being directed by his reason. Now it is manifest that the outward movements of man are dirigible by reason, since the outward members are set in motion at the command of reason. Hence it is evident that there is a moral virtue concerned with the direction of these movements.
Now the direction of these movements may be considered from a twofold standpoint. First, in respect of fittingness to the person; secondly, in respect of fittingness to externals, whether persons, business, or place. Hence Ambrose says (De Offic. i, 18): "Beauty of conduct consists in becoming behavior towards others, according to their sex and person," and this regards the first. As to the second, he adds: "This is the best way to order our behavior, this is the polish becoming to every action."
Hence Andronicus [De Affectibus] ascribes two things to these outward movements: namely "taste" [ornatus] which regards what is becoming to the person, wherefore he says that it is the knowledge of what is becoming in movement and behavior; and "methodicalness" [bona ordinatio] which regards what is becoming to the business in hand, and to one's surroundings, wherefore he calls it "the practical knowledge of separation," i.e. of the distinction of "acts."
Reply to Objection 1. Outward movements are signs of the inward disposition, according to Sirach 19:27, "The attire of the body, and the laughter of the teeth, and the gait of the man, show what he is"; and Ambrose says (De Offic. i, 18) that "the habit of mind is seen in the gesture of the body," and that "the body's movement is an index of the soul."
Reply to Objection 2. Although it is from natural disposition that a man is inclined to this or that style of outward movement, nevertheless what is lacking to nature can be supplied by the efforts of reason. Hence Ambrose says (De Offic. i, 18): "Let nature guide the movement: and if nature fail in any respect, surely effort will supply the defect."
Reply to Objection 3. As stated (ad 1) outward movements are indications of the inward disposition, and this regards chiefly the passions of the soul. Wherefore Ambrose says (De Offic. i, 18) that "from these things," i.e. the outward movements, "the man that lies hidden in our hearts is esteemed to be either frivolous, or boastful, or impure, or on the other hand sedate, steady, pure, and free from blemish." It is moreover from our outward movements that other men form their judgment about us, according to Sirach 19:26, "A man is known by his look, and a wise man, when thou meetest him, is known by his countenance." Hence moderation of outward movements is directed somewhat to other persons, according to the saying of Augustine in his Rule (Ep. ccxi), "In all your movements, let nothing be done to offend the eye of another, but only that which is becoming to the holiness of your state." Wherefore the moderation of outward movements may be reduced to two virtues, which the Philosopher mentions in Ethic. iv, 6,7. For, in so far as by outward movements we are directed to other persons, the moderation of our outward movements belongs to "friendliness or affability" [Cf. 114, 1]. This regards pleasure or pain which may arise from words or deeds in reference to others with whom a man comes in contact. And, in so far as outward movements are signs of our inward disposition, their moderation belongs to the virtue of truthfulness [Cf. 9], whereby a man, by word and deed, shows himself to be such as he is inwardly.
Reply to Objection 4. It is censurable to study the style of one's outward movements, by having recourse to pretense in them, so that they do not agree with one's inward disposition. Nevertheless it behooves one to study them, so that if they be in any way inordinate, this may be corrected. Hence Ambrose says (De Offic. i, 18): "Let them be without artifice, but not without correction."
Source: Summa Theologica (New Advent)