St. Ambrose, treating of the words in the Gospel concerning eunuchs, condemns those who make themselves such. Those only deserve praise who have through continence gained the victory over themselves, but no one is to be compelled to live this life, as neither Christ nor the Apostle laid down such a law, so that the marriage vow is not to be blamed, though that of chastity is better.
75. So, then, a commandment to this effect is not given, but a counsel is. Chastity is commanded, entire continence counselled. “But all men cannot receive this saying, but they to whom it is given. For there are eunuchs which were so born from their mothers womb,” in whom exists a natural necessity not the virtue of chastity. “And there are eunuchs who have made themselves eunuchs,” of their own will, that is, not of necessity. “And there are eunuchs which were made eunuchs of men....” And, therefore, great is the grace of continence in them, because it is the will, not incapacity, which makes a man continent. For it is seemly to preserve the gift of divine working whole. And let them not think it too little not to be impeded by the inclination of the body, for if the reward for going through that conflict is taken from their reach, the matter of sin is also removed, and though they cannot receive the crown, no more can they be overcome. They have other kinds of virtues by which they ought to commend themselves if their faith be firm, their mercifulness abundant, avarice far from them, grace abundant. But in them there is no fault, for they are ignorant of the act of sin.
76. The case is not the same of those who mutilate themselves, and I touch upon this point advisedly, for there are some who look upon it as a holy deed to check by the evil violence of this sort. And though I am not willing to express my own opinion concerning them, though decisions of our forefathers are in existence; but then consider whether this tends not rather to a declaration of weakness than to a reputation for strength. On this principle no one should fight lest he be overcome, nor make use of his feet, fearing the danger of stumbling, nor let his eyes do their office because he fears a fall through lust. But what does it profit to cut the flesh, when there may be guilt even in a look? “For whosoever looks on a woman to lust after her has committed adultery already with her in his heart.” And likewise she who looks on a man to lust after him commits adultery. It becomes us, then, to be chaste, not weak, to have our eyes modest, not feeble.
77. No one, then, ought, as many suppose, to mutilate himself, but rather gain the victory; for the Church gathers in those who conquer, not those who are defeated. And why should I use arguments when the words of the Apostle's command are at hand? For you find it thus written: “I would that they were mutilated who desire that you should be circumcised.” For why should the means of gaining a crown and of the practice of virtue be lost to a man who is born to honour, equipped for victory? How can he through courage of soul mutilate himself? “There be eunuchs which have made themselves eunuchs for the kingdom of heaven's sake.”
78. This, however, is not a commandment given to all, but a wish set before all. For he who commands must always keep to the exact scope of the commandments, and he who distributes tasks must observe equity in looking into them, for: “A false balance is abomination to the Lord.” There is, then, an excess and a defect in weight, but the Church accepts neither, for: “Excessive and defective weights and various measures, both of them are alike abominable in the sight of the Lord.” There are tasks which wisdom apportions, and apportions according to the estimate of the virtue and strength of each. “He that is able to receive it let him receive it.”
79. For the Creator of all knows that the dispositions of each are different, and therefore incited virtue by rewards, instead of binding weakness by chains. And he, the teacher of the Gentiles, the good guide of our conduct, and instructor of our inmost affections, who had learned in himself that the law of the flesh resists the law of the mind, but yields to the grace of Christ, he knows, I say, that various movements of the mind are opposed to each other; and, therefore, so expresses his exhortations to chastity, as not to do away with the grace of marriage, nor has he so exalted marriage as to check the desire of chastity. But beginning with the recommendation of chastity, he goes on to remedies against incontinence, and having set before the stronger the prize of their high calling, he suffers no one to faint by the way; approving those who take the lead so as not to make little of those who follow. For he, himself, had learned that the Lord Jesus gave to some barley bread lest they should faint by the way, and administered His Body to others, that they might strive for the kingdom.
80. For the Lord Himself did not impose this commandment, but invited the will, and the Apostle did not lay down a rule, but gave a counsel. But this not a man's counsel as to things within the compass of man's strength, for he acknowledges that the gift of divine mercy was bestowed upon him, that he might know how faithfully to set first the former, and to arrange the latter. And, therefore, he says: “I think,” not, I order, but, “I think that this is good because of the present distress.”
81. The marriage bond is not then to be shunned as though it were sinful, but rather declined as being a galling burden. For the law binds the wife to bear children in labour and in sorrow, and is in subjection to her husband, for that he is lord over her. So, then, the married woman, but not the widow, is subject to labour and pain in bringing forth children, and she only that is married, not she that is a virgin, is under the power of her husband. The virgin is free from all these things, who has vowed her affection to the Word of God, who awaits the Spouse of blessing with her lamp burning with the light of a good will. And so she is moved by counsels, not bound by chains.
Source: Concerning Widows (New Advent)