Commentaria in Summam contra Gentiles, Liber III

After St. Thomas has shown that marriage is natural to man, he wishes to determine concerning the conditions of marriage ¹. And he lays down four conditions in these four chapters.

I. The first is that marriage ought to be indivisible and indissoluble: or, it ought to endure through the whole of life, which is the same thing. Now, with respect to declaring this, he does two things: first, he proves that according to the inclination of nature marriage ought to be indissoluble; second, he proves that such indissolubility is fittingly instituted by human and divine laws ².

As to the first, he argues first thus. It is natural that the father's solicitude for the son should remain until the end of his life. Therefore the natural order requires that in the human species the father and the mother remain together until the end of life.

The consequence is proved. Because even in birds the father's solicitude for the offspring causes the staying together of male and female. — But the antecedent is proved. Because, since natural life, which cannot be perpetually preserved in the father, is preserved as it were by a kind of succession in the son, it is fitting according to nature that the son should also succeed in those things that belong to the father, namely possessions ordered to the preservation of natural life.

It should be noted that, because the education of the offspring and its governance is not fittingly carried out by the father unless the work of the mother also concurs, since the offspring is their common good and needs both; so long as the father's solicitude for the son lasts, the father is inclined by nature to remain together with the mother, without whom there would not be a fitting education of the son. And therefore, if according to nature the father's solicitude for the son is throughout the whole life of the father, in which the father lays up treasure for the son ³, it is according to the inclination of nature that he should also remain together with the female through the whole time of his life. And this is the foundation of this reason.

II. Second. The dissolution of the aforesaid partnership is contrary to natural equity. Therefore etc. — The antecedent is proved. The female needs the male not only for the sake of generation, but also for the sake of governance: because the male is more perfect in reason and stronger in virtue. But the woman is taken into the partnership of the man on account of the necessity of generation. But, once the woman's fecundity and beauty cease, she is hindered from being taken by another. Therefore harm would be inflicted on the woman, contrary to natural equity, if she were dismissed by the man.

It should be noted that natural equity requires that from a benefit the benefactor should receive gratitude and advantage from the one to whom the benefit is done, but not harm. Therefore it is contrary to natural equity that harm be inflicted on a benefactor from her benefit. But if the woman, after her fecundity and beauty, which she gave for the man's benefit by offering herself to him as a partner for generation, were dismissed by the man, harm would be inflicted on her from her benefit: because, needing the man as a governor, after the time of fecundity and beauty, she would not find one by whom she might be taken, and by whom she might be governed. Therefore such a dismissal would be contrary to natural equity. And in this the reason consists.

Third. It would be contrary to natural order if the woman could leave the man. Therefore, if the man could leave the woman, there would not be an equal partnership of the man to the woman, but a kind of servitude on the part of the woman. — The antecedent is proved. Because it is not in the power of him who is subjected to another to depart from his rule. But the woman is naturally subject to the man as to a governor.

III. Fourth. Those things that impede certainty of offspring are contrary to the natural instinct of the human species. But if the man could dismiss the woman and the woman the man, and be joined to another, certainty of offspring would be impeded. Therefore etc. — The major is proved. Because, since the son needs the long-lasting governance of the father, there is in men a natural solicitude concerning certainty of offspring. — But the minor is proved. Because the woman known by the first would afterwards be known by the second.

2. But this reason seems to be ineffective. For certainty of offspring is not removed unless, before the offspring is born, the woman is known by another. For after the offspring is born, if the woman is known by another, certainty of the offspring previously born is not removed on this account. And thus by this reason a perpetual and indivisible partnership of the male to the female is not concluded, but only a partnership and indissolubility before the generation of the offspring.

He answers that this reason does not conclude directly that the partnership of the man and the woman must last through the whole of life, but that there is a certain mutual obligation between them such that the woman is so bound to the first man that she cannot be joined to another than him—and consequently, if there ought to be an equal partnership, neither can the man be joined to another woman—because by the intercourse of the woman with another man certainty of offspring would be removed. But from the fact that the woman and the man are mutually bound to one another at the time when they are fit for generation, St. Thomas leaves it manifest from the preceding reasons that this kind of partnership must also endure through the whole of life.

3. Fifth. The greatest friendship seems to exist between husband and wife: on account of their unification not only in the act of carnal copulation, which even among beasts causes a kind of sweet friendship ⁴; but also for the consortium of the whole domestic life. A sign of this is that for the sake of his wife a man leaves father and mother, as is said in Gen. 2. Therefore etc. — The consequence is proved. Because friendship, the greater it is, ought to be the firmer and longer-lasting.

IV. In the second place St. Thomas shows that it was necessary to be ordained by human and divine law that marriage be indissoluble, and also that it be of one with one ⁵.

Now he proves this in a twofold way ⁶. First. Those things that pertain to the generation of offspring must be ordained by laws both divine and human. But human laws proceed from natural instinct: as is shown from demonstrative sciences. Divine laws, however, not only unfold the instinct of nature, but also supply the defects ⁷ of natural instinct. Therefore by these laws that which is according to natural instinct ought to be ordained concerning generation. But the natural instinct in the human species is that the union of male and female be indivisible, and of one with one. Therefore this ought to have been ordained by human law. To this, however, divine law adds a certain supernatural reason, from the signification of the inseparable union of Christ and the Church, if it is of one with one.

The assumption is proved. Because law is instituted for the common good. But among natural acts only generation is ordered to the common good, namely to the preservation of the species.

From this reason St. Thomas infers that, because inordinations concerning the act of generation not only oppose natural instinct, but also transgress divine and human laws, there is more sin committed concerning this from inordination than concerning the taking of food, or other things of this kind.

2. Concerning that which is said, that human laws proceed from natural instinct, it must be considered, from the doctrine of St. Thomas, Ia IIae, q. 95, a. 2, that this is understood not of an unjust law (which properly speaking is not to be called a law, but rather a corruption of law), but of a just law. For since something is called just from the fact that it is right according to the rule of reason; and the first rule of reason is the law of nature: every law humanly posited has so much of the nature of law as it is derived from the law of nature. — Now, how some laws are derived in diverse ways from the natural law, St. Thomas shows in the same place.

3. Concerning that which is said, that the divine law adds to the indivisibility of the union of male and female which is ordained by human law a certain supernatural reason from the signification of the inseparability of the union of Christ and the Church, if it is of one with one, two things are to be noted. One is from the doctrine of St. Thomas in the Fourth Book, d. 33, q. 2, a. 1 ⁸, that the inseparability of man and woman is considered in one way in marriage according as it is an office of nature, in which way its determination belongs to human law; and in another way according as it is a sacrament of the Church, according to which way it belongs to divine law. For in the first way, inseparability is not of the primary intention of marriage: because it is not ordered to the procreation of offspring and its education and instruction until it reaches the perfect age, which is of the primary intention of nature, for this could be without such a perpetual partnership: but it is ordered to this, that provision be made for it in the future through the whole of its life, namely through the leaving of an inheritance and other goods, which seems to be of the secondary intention of nature. — But in the second way, inseparability is of the primary intention of marriage. For it is primarily intended in marriage, according as it is an instituted sacrament of the Church, that through it the indivisibility of the union of Christ and the Church be signified: and this is signified through the indivisibility of marriage. And because the sacraments were instituted through divine law, therefore it is fittingly said that this reason of signification is added to the indivisibility of marriage.

The other is that, because a divine dispensation was sometimes granted regarding a plurality of wives, and could also be dispensed; if a dispensation were granted regarding a plurality of wives, and consequently the partnership of marriage were not indivisible, the sacrament of marriage would not signify the indivisibility of the union of Christ and the Church, because it would not signify the union of Christ and the Church inasmuch as it is one: although it could signify such a union inasmuch as there is a distinction of degrees in the Church, as St. Thomas says in the Fourth Book, d. 33, a. 2 ⁹. But if it is only of one with one, as is instituted through the law of Christ, such indivisibility of the union of Christ and the Church is signified through this kind of indivisibility of marriage. Therefore St. Thomas added, if it is of one with one.

V. Second. The union of male and female is not only ordained by laws according as it pertains to generating offspring, but also according as it pertains to good morals, which right reason disposes. But the indivisible union of male and female pertains to good morals: because thus the love of the one for the other is more faithful; there is more solicitous care of both in domestic affairs; the origins of discords between the man and the relatives of the wife are removed, and affection among in-laws becomes firmer; occasions of adulteries are also removed. Therefore etc. — The major is proved. Because all other things ought to be ordered to that which is best in man.

VI. The conclusion is confirmed by the authority of Matt. 19 and 1 Cor. 7.

Now by this the custom of those who dismiss their wives is excluded. And although this was permitted to the Jews in the Old Law, this was on account of the hardness of their heart, to avoid a greater evil: because, namely, they were prone to the killing of their wives.

For the evidence of this, it must be considered, from the doctrine of St. Thomas, IV Sent., in the cited article, quaestiuncula 2 ¹⁰, that there was a twofold opinion concerning the bill of divorce permitted to the Jews. For some said that the Jews did not sin in repudiating their wives, but it was lawful for them by divine permission: because this was not indicated by the law or the prophets to be a sin. And this opinion has a foundation from the words of Chrysostom, saying that the lawgiver took away the fault from the sin when he permitted divorce ¹¹. — Others, however, said that those giving a bill of divorce were not excused from sin, although they were excused from the punishment to be inflicted according to the laws. Whence they say that Moses permitted the bill of divorce to the Jews to restrain a greater evil, namely uxoricide: just as it was permitted to them to lend on usury to strangers, lest they should lend on usury to their brothers. — But although, as St. Thomas says in the same place, the first opinion is probable, the second nevertheless is more commonly held. And therefore he seems to follow it in this place, while he says that a lesser evil was permitted to exclude a greater evil.