As promised, here are some quotes from St. Augustine’s Of the Good of Marriage. New Advent explains that Augustine’s work is in response both to St. Jerome’s writing on the subject, as well as the original piece by Jovinianus that Jerome was responding to:
This treatise, and the following, were written against somewhat that still remained of the heresy of Jovinian. S. Aug. mentions this error in b. ii. c. 23, de Nuptiis et Conc. “Jovinianus,” he says, “who a few years since tried to found a new heresy, said that the Catholics favored the Manichæans, because in opposition to him they preferred holy Virginity to Marriage.” And in his book on Heresies, c. 82. “That heresy took its rise from one Jovinianus, a Monk, in our own time, when we were yet young.” And he adds that it was soon overborne and extinguished, say about A.D. 390, having been condemned first at Rome, then at Milan. There are letters of Pope Siricius on the subject to the Church of Milan, and the answer sent him by the Synod of Milan, at which St. Ambrose presided. Jerome had refuted Jovinian, but was said to have attempted the defense of the excellency of the virgin state, at the expense of condemning marriage. That Augustine might not be subject to any such complaint or calumny, before speaking of the superiority of Virginity, he thought it well to write on the Good of Marriage.
Augustine allows for two ways a person can have sex in marriage without sinning. The first is if the person is having sex not for pleasure, but to create a child (all emphasis mine):
For intercourse of marriage for the sake of begetting has not fault; but for the satisfying of lust, but yet with husband or wife, by reason of the faith of the bed, it has venial fault: but adultery or fornication has deadly fault, and, through this, continence from all intercourse is indeed better even than the intercourse of marriage itself, which takes place for the sake of begetting.
The other time Augustine explains one can have sex in marriage without sinning is if they are only having sex out of duty. Specifically, he is talking about a scenario where one spouse wants to have sex not specifically to have a child, but out of sexual desire. The spouse who wants sex in that scenario is sinning, but this is a minor sin. The spouse who only has duty sex however is not sinning. Given that Augustine says it is better to abstain even from pro-creative sex, unwanted sex for the sake of the marital debt is the only time a married person can not only not sin by having sex, but can also be doing what is best:
But because that Continence is of larger desert, but to pay the due of marriage is no crime, but to demand it beyond the necessity of begetting is a venial fault, but to commit fornication or adultery is a crime to be punished…
Augustine explains that an unmarried woman who has sex not for pleasure, but only to become pregnant with an illegitimate child, is more worthy than a married woman who has sex with her husband out of sexual desire:
But further, if from that intercourse, so far as pertains to herself, she has no wish but for sons, and suffers unwilling whatever she suffers beyond the cause of begetting; there are many matrons to whom she is to be preferred; who, although they are not adulteresses, yet force their husbands, for the most part also wishing to exercise continence, to pay the due of the flesh, not through desire of children, but through glow of lust making an intemperate use of their very right…
Augustine extends this comparison to a husband who has sex with his wife while she is pregnant. A woman who fornicates but doesn’t like it is better than a man who has sex with his wife for pleasure:
For, although it be shameful to wish to use a husband for purposes of lust, yet it is honorable to be unwilling to have intercourse save with an husband, and not to give birth to children save from a husband. There are also men incontinent to that degree, that they spare not their wives even when pregnant.
He also argues that certain sexual sins are less sinful if combined with other sexual sins. Therefore it is less sinful to have “unnatural” sex with a harlot (combining unnatural sex with fornication) than with your wife:
12. For, whereas that natural use, when it pass beyond the compact of marriage, that is, beyond the necessity of begetting, is pardonable in the case of a wife, damnable in the case of an harlot; that which is against nature is execrable when done in the case of an harlot, but more execrable in the case of a wife. Of so great power is the ordinance of the Creator, and the order of Creation, that, in matters allowed us to use, even when the due measure is exceeded, it is far more tolerable, than, in what are not allowed, either a single, or rare excess. And, therefore, in a matter allowed, want of moderation, in a husband or wife, is to be borne with, in order that lust break not forth into a matter that is not allowed. Hence is it also that he sins far less, who is ever so unceasing in approaches to his wife, than he who approaches ever so seldom to commit fornication. But, when the man shall wish to use the member of the wife not allowed for this purpose, the wife is more shameful, if she suffer it to take place in her own case, than if in the case of another woman.
Note that there is also the message that the wife should be in control*.
Augustine’s permission even for natural sex is given grudgingly. He urges married couples to stop having sex at as young an age as possible:
But now in good, although aged, marriage, albeit there has withered away the glow of full age between male and female, yet there lives in full vigor the order of charity between husband and wife: because, the better they are, the earlier they have begun by mutual consent to contain from sexual intercourse with each other: not that it should be matter of necessity afterwards not to have power to do what they would, but that it should be matter of praise to have been unwilling at the first, to do what they had power to do.
At the center of the controversy for both Augustine and Jerome is Jovinian’s claim that:
virgins, widows, and married women, who have been once passed through the laver of Christ, if they are on a par in other respects, are of equal merit.
Having explained that marriage is not intrinsically sinful, Augustine gets on with the business of explaining that men and women today who marry are less holy than men and women who married in the times of the Old Testament:
19. Therefore as many women as there are now, unto whom it is said, if they contain not, let them be married, are not to be compared to the holy women then, even when they married. Marriage itself indeed in all nations is for the same cause of begetting sons, and of what character soever these may be afterward, yet was marriage for this purpose instituted, that they may be born in due and honest order. But men, who contain not, as it were ascend unto marriage by a step of honesty: but they, who without doubt would contain, if the purpose of that time had allowed this, in a certain measure descended unto marriage by a step of piety. And, on this account, although the marriages of both, so far as they are marriages, in that they are for the sake of begetting, are equally good, yet these men when married are not to be compared with those men as married. For these have, what is allowed them by the way of leave, on account of the honesty of marriage, although it pertain not to marriage; that is, the advance which goes beyond the necessity of begetting, which they had not. But neither can these, if haply there be now any found, who neither seek, nor desire, in marriage any thing, save that wherefore marriage was instituted, be made equal to those men. For in these the very desire of sons is carnal, but in those it was spiritual, in that it was suited to the sacrament of that time. Forsooth now no one who is made perfect in piety seeks to have sons, save after a spiritual sense; but then it was the work of piety itself to beget sons even after a carnal sense: in that the begetting of that people was fraught with tidings of things to come, and pertained unto the prophetic dispensation.
*The full scope of this problem is visible when you consider the potentially expansive meaning of “unnatural” given that according to Augustine the only truly sinless reason for marital sex is out of a desire to have children (otherwise at least one spouse is sinning). Under that constraint, anything which goes beyond P in V sex for the purpose of achieving ejaculation inside the vagina could rightly be considered unnatural. While RCC Doctrine (HT ACThinker) includes both procreation and unitive purposes as valid reasons for marital sex, there are some even today who make this very argument:
So, for example, a husband cannot deliberately stimulate the genital organs of his wife in order to give her sexual pleasure, for such an action is defined within the Catechism as a type of sexual act which is “intrinsically and gravely disordered.”