Objection 1. It would seem that a fruit is not due to the virtue of continence alone. For a gloss on 1 Corinthians 15:41, "One is the glory of the sun," says that "the worth of those who have the hundredfold fruit is compared to the glory of the sun; to the glory of the moon those who have the sixtyfold fruit; and to the stars those who have the thirtyfold fruit." Now this difference of glory, in the meaning of the Apostle, regards any difference whatever of beatitude. Therefore the various fruits should correspond to none but the virtue of continence.
Objection 2. Further, fruits are so called from fruition. But fruition belongs to the essential reward which corresponds to all the virtues. Therefore, etc.
Objection 3. Further, fruit is due to labor: "The fruit of good labors is glorious" (Wisdom 3:15). Now there is greater labor in fortitude than in temperance or continence. Therefore fruit does not correspond to continence alone.
Objection 4. Further, it is more difficult not to exceed the measure in food which is necessary for life, than in sexual matters without which life can be sustained: and thus the labor of frugality is greater than that of continence. Therefore fruit corresponds to frugality rather than to continence.
Objection 5. Further, fruit implies delight, and delight regards especially the end. Since then the theological virtues have the end for their object, namely God Himself, it would seem that to them especially the fruit should correspond.
On the contrary, is the statement of the gloss on Matthew 13:23, "The one a hundredfold," which assigns the fruits to virginity, widowhood, and conjugal continence, which are parts of continence.
I answer that, A fruit is a reward due to a person in that he passes from the carnal to the spiritual life. Consequently a fruit corresponds especially to that virtue which more than any other frees man from subjection to the flesh. Now this is the effect of continence, since it is by sexual pleasures that the soul is especially subject to the flesh; so much so that in the carnal act, according to Jerome (Ep. ad Ageruch.), "not even the spirit of prophecy touches the heart of the prophet," nor "is it possible to understand anything in the midst of that pleasure," as the Philosopher says (Ethic. vii, 11). Therefore fruit corresponds to continence rather than to another virtue.
Reply to Objection 1. This gloss takes fruit in a broad sense, according as any reward is called a fruit.
Reply to Objection 2. Fruition does not take its name from fruit by reason of any comparison with fruit in the sense in which we speak of it now, as evidenced by what has been said.
Reply to Objection 3. Fruit, as we speak of it now, corresponds to labor not as resulting in fatigue, but as resulting in the production of fruit. Hence a man calls his crops his labor, inasmuch as he labored for them, or produced them by his labor. Now the comparison to fruit, as produced from seed, is more adapted to continence than to fortitude, because man is not subjected to the flesh by the passions of fortitude, as he is by the passions with which continence is concerned.
Reply to Objection 4. Although the pleasures of the table are more necessary than the pleasures of sex, they are not so strong: wherefore the soul is not so much subjected to the flesh thereby.
Reply to Objection 5. Fruit is not taken here in the sense in which fruition applies to delight in the end; but in another sense as stated above (Article 2). Hence the argument proves nothing.
Source: Summa Theologica (New Advent)