Objection 1. It would seem that virginity is not more excellent than marriage. For Augustine says (De Bono Conjug. xxi): "Continence was equally meritorious in John who remained unmarried and Abraham who begot children." Now a greater virtue has greater merit. Therefore virginity is not a greater virtue than conjugal chastity.
Objection 2. Further, the praise accorded a virtuous man depends on his virtue. If, then, virginity were preferable to conjugal continence, it would seem to follow that every virgin is to be praised more than any married woman. But this is untrue. Therefore virginity is not preferable to marriage.
Objection 3. Further, the common good takes precedence of the private good, according to the Philosopher (Ethic. i, 2). Now marriage is directed to the common good: for Augustine says (De Bono Conjug. xvi): "What food is to a man's wellbeing, such is sexual intercourse to the welfare of the human race." On the other hand, virginity is ordered to the individual good, namely in order to avoid what the Apostle calls the "tribulation of the flesh," to which married people are subject (1 Corinthians 7:28). Therefore virginity is not greater than conjugal continence.
On the contrary, Augustine says (De Virgin. xix): "Both solid reason and the authority of Holy Writ show that neither is marriage sinful, nor is it to be equaled to the good of virginal continence or even to that of widowhood."
I answer that, According to Jerome (Contra Jovin. i) the error of Jovinian consisted in holding virginity not to be preferable to marriage. This error is refuted above all by the example of Christ Who both chose a virgin for His mother, and remained Himself a virgin, and by the teaching of the Apostle who (1 Corinthians 7) counsels virginity as the greater good. It is also refuted by reason, both because a Divine good takes precedence of a human good, and because the good of the soul is preferable to the good of the body, and again because the good of the contemplative life is better than that of the active life. Now virginity is directed to the good of the soul in respect of the contemplative life, which consists in thinking "on the things of God" [Vulgate: 'the Lord'], whereas marriage is directed to the good of the body, namely the bodily increase of the human race, and belongs to the active life, since the man and woman who embrace the married life have to think "on the things of the world," as the Apostle says (1 Corinthians 7:34). Without doubt therefore virginity is preferable to conjugal continence.
Reply to Objection 1. Merit is measured not only by the kind of action, but still more by the mind of the agent. Now Abraham had a mind so disposed, that he was prepared to observe virginity, if it were in keeping with the times for him to do so. Wherefore in him conjugal continence was equally meritorious with the virginal continence of John, as regards the essential reward, but not as regards the accidental reward. Hence Augustine says (De Bono Conjug. xxi) that both "the celibacy of John and the marriage of Abraham fought Christ's battle in keeping with the difference of the times: but John was continent even in deed, whereas Abraham was continent only in habit."
Reply to Objection 2. Though virginity is better than conjugal continence, a married person may be better than a virgin for two reasons. First, on the part of chastity itself; if to wit, the married person is more prepared in mind to observe virginity, if it should be expedient, than the one who is actually a virgin. Hence Augustine (De Bono Conjug. xxii) charges the virgin to say: "I am no better than Abraham, although the chastity of celibacy is better than the chastity of marriage." Further on he gives the reason for this: "For what I do now, he would have done better, if it were fitting for him to do it then; and what they did I would even do now if it behooved me now to do it." Secondly, because perhaps the person who is not a virgin has some more excellent virtue. Wherefore Augustine says (De Virgin. xliv): "Whence does a virgin know the things that belong to the Lord, however solicitous she be about them, if perchance on account of some mental fault she be not yet ripe for martyrdom, whereas this woman to whom she delighted in preferring herself is already able to drink the chalice of the Lord?"
Reply to Objection 3. The common good takes precedence of the private good, if it be of the same genus: but it may be that the private good is better generically. It is thus that the virginity that is consecrated to God is preferable to carnal fruitfulness. Hence Augustine says (De Virgin. ix): "It must be confessed that the fruitfulness of the flesh, even of those women who in these times seek naught else from marriage but children in order to make them servants of Christ, cannot compensate for lost virginity."
Source: Summa Theologica (New Advent)