Accordingly we reply to the Sixth Objection that human nature was founded without any defect, and consequently it is endowed not only with those things without which the principal end of marriage is impossible of attainment, but also with those without which the secondary end of marriage could not be obtained without difficulty: and in this way it sufficed man when he was first formed to have one wife, as stated above.
Reply to Objection 7: In marriage the husband gives his wife power of his body, not in all respects, but only in those things that are required by marriage. Now marriage does not require the husband to pay the debt every time his wife asks for it, if we consider the principal end for which marriage was instituted, namely the good of the offspring, but only as far as is necessary for impregnation. But in so far as it is instituted as a remedy (which is its secondary end), marriage does require the debt to be paid at all times on being asked for. Hence it is evident that by taking several wives a man does not bind himself to the impossible, considering the principal end of marriage; and therefore plurality of wives is not against the first principles of the natural law.
Reply to Objection 8: This precept of the natural law, "Do not to another what thou wouldst not were done to thyself," should be understood with the proviso that there be equal proportion. For if a superior is unwilling to be withstood by his subject, he is not therefore bound not to withstand his subject. Hence it does not follow in virtue of this precept that as a husband is unwilling for his wife to have another husband, he must not have another wife: because for one man to have several wives is not contrary to the first principles of the natural law, as stated above: whereas for one wife to have several husbands is contrary to the first principles of the natural law, since thereby the good of the offspring which is the principal end of marriage is, in one respect, entirely destroyed, and in another respect hindered. For the good of the offspring means not only begetting, but also rearing. Now the begetting of offspring, though not wholly voided (since a woman may be impregnated a second time after impregnation has already taken place, as stated in De Gener. Animal. vii. 4), is nevertheless considerably hindered, because this can scarcely happen without injury either to both fetus or to one of them. But the rearing of the offspring is altogether done away, because as a result of one woman having several husbands there follows uncertainty of the offspring in relation to its father, whose care is necessary for its education. Wherefore the marriage of one wife with several husbands has not been sanctioned by any law or custom, whereas the converse has been.
Reply to Objection 9: The natural inclination in the appetitive power follows the natural concept in the cognitive power. And since it is not so much opposed to the natural concept for a man to have several wives as for a wife to have several husbands, it follows that a wife's love is not so averse to another sharing the same husband with her, as a husband's love is to another sharing the same wife with him. Consequently both in man and in other animals the male is more jealous of the female than "vice versa."
Whether it was ever lawful to have several wives?
Objection 1: It would seem that it can never have been lawful to have several wives. For, according to the Philosopher (Ethic. v, 7), "The natural law has the same power at all times and places." Now plurality of wives is forbidden by the natural law, as stated above (A[1]). Therefore as it is unlawful now, it was unlawful at all times.
Objection 2: Further, if it was ever lawful, this could only be because it was lawful either in itself, or by dispensation. If the former, it would also be lawful now; if the latter, this is impossible, for according to Augustine (Contra Faust. xxvi, 3), "as God is the founder of nature, He does nothing contrary to the principles which He has planted in nature." Since then God has planted in our nature the principle that one man should be united to one wife, it would seem that He has never dispensed man from this.
Objection 3: Further, if a thing be lawful by dispensation, it is only lawful for those who receive the dispensation. Now we do not read in the Law of a general dispensation having been granted to all. Since then in the Old Testament all who wished to do so, without any distinction, took to themselves several wives, nor were reproached on that account, either by the law or by the prophets, it would seem that it was not made lawful by dispensation.
Objection 4: Further, where there is the same reason for dispensation, the same dispensation should be given. Now we cannot assign any other reason for dispensation than the multiplying of the offspring for the worship of God, and this is necessary also now. Therefore this dispensation would be still in force, especially as we read nowhere of its having been recalled.
Objection 5: Further, in granting a dispensation the greater good should not be overlooked for the sake of a lesser good. Now fidelity and the sacrament, which it would seem impossible to safeguard in a marriage where one man is joined to several wives, are greater goods than the multiplication of the offspring. Therefore this dispensation ought not to have been granted with a view to this multiplication.
On the contrary, It is stated ( Gal. 3:19 ) that the Law "was set because of transgressors [Vulg.: 'transgressions']," namely in order to prohibit them. Now the Old Law mentions plurality of wives without any prohibition thereof, as appears from Dt. 21:15, "If a man have two wives," etc. Therefore they were not transgressors through having two wives; and so it was lawful.
Further, this is confirmed by the example of the holy patriarchs, who are stated to have had several wives, and yet were most pleasing to God, for instance Jacob, David, and several others. Therefore at one time it was lawful.
I answer that, As stated above (A[1], ad 7,8), plurality of wives is said to be against the natural law, not as regards its first precepts, but as regards the secondary precepts, which like conclusions are drawn from its first precepts. Since, however, human acts must needs vary according to the various conditions of persons, times, and other circumstances, the aforesaid conclusions do not proceed from the first precepts of the natural law, so as to be binding in all cases, but only in the majority. for such is the entire matter of Ethics according to the Philosopher (Ethic. i, 3,7). Hence, when they cease to be binding, it is lawful to disregard them. But because it is not easy to determine the above variations, it belongs exclusively to him from whose authority he derives its binding force to permit the non-observance of the law in those cases to which the force of the law ought not to extend, and this permission is called a dispensation. Now the law prescribing the one wife was framed not by man but by God, nor was it ever given by word or in writing, but was imprinted on the heart, like other things belonging in any way to the natural law. Consequently a dispensation in this matter could be granted by God alone through an inward inspiration, vouchsafed originally to the holy patriarchs, and by their example continued to others, at a time when it behooved the aforesaid precept not to be observed, in order to ensure the multiplication of the offspring to be brought up in the worship of God. For the principal end is ever to be borne in mind before the secondary end. Wherefore, since the good of the offspring is the principal end of marriage, it behooved to disregard for a time the impediment that might arise to the secondary ends, when it was necessary for the offspring to be multiplied; because it was for the removal of this impediment that the precept forbidding a plurality of wives was framed, as stated above (A[1]).
Reply to Objection 1: The natural law, considered in itself, has the same force at all times and places; but accidentally on account of some impediment it may vary at certain times and places, as the Philosopher (Ethic. i, 3,7) instances in the case of other natural things. For at all times and places the right hand is better than the left according to nature, but it may happen accidentally that a person is ambidextrous, because our nature is variable; and the same applies to the natural, just as the Philosopher states (Ethic. i, 3,7).
Reply to Objection 2: In a Decretal (De divortiis, cap. Gaudemus) it is asserted that is was never lawful to have several wives without having a dispensation received through Divine inspiration. Nor is the dispensation thus granted a contradiction to the principles which God has implanted in nature, but an exception to them, because those principles are not intended to apply to all cases but to the majority, as stated. Even so it is not contrary to nature when certain occurrences take place in natural things miraculously, by way of exception to more frequent occurrences.
Reply to Objection 3: Dispensation from a law should follow the quality of the law. Wherefore, since the law of nature is imprinted on the heart, it was not necessary for a dispensation from things pertaining to the natural law to be given under the form of a written law but by internal inspiration.
Reply to Objection 4: When Christ came it was the time of the fulness of the grace of Christ, whereby the worship of God was spread abroad among all nations by a spiritual propagation. Hence there is not the same reason for a dispensation as before Christ's coming, when the worship of God was spread and safeguarded by a carnal propagation.
Reply to Objection 5: The offspring, considered as one of the marriage goods, includes the keeping of faith with God, because the reason why it is reckoned a marriage good is because it is awaited with a view to its being brought up in the worship of God. Now the faith to be kept with God is of greater import than the faith to be kept with a wife, which is reckoned a marriage good, and than the signification which pertains to the sacrament, since the signification is subordinate to the knowledge of faith. Hence it is not unfitting if something is taken from the two other goods for the sake of the good of the offspring. Nor are they entirely done away, since there remains faith towards several wives; and the sacrament remains after a fashion, for though it did not signify the union of Christ with the Church as one, nevertheless the plurality of wives signified the distinction of degrees in the Church, which distinction is not only in the Church militant but also in the Church triumphant. Consequently their marriages signified somewhat the union of Christ not only with the Church militant, as some say, but also with the Church triumphant where there are "many mansions" [* Jn. 19:2 ].
Whether it is against the natural law to have a concubine?
Objection 1: It would seem that to have a concubine is not against the natural law. For the ceremonies of the Law are not of the natural law. But fornication is forbidden ( Acts 15:29 ) in conjunction with ceremonies of the law which for the time were being imposed on those who were brought to the faith from among the heathens. Therefore simple fornication which is intercourse with a concubine is not against the natural law.
Objection 2: Further, positive law is an outcome of the natural law, as Tully says (De Invent. ii). Now fornication was not forbidden by positive law; indeed according to the ancient laws women used to be sentenced to be taken to brothels. Therefore it is not against the natural law to have a concubine.
Objection 3: Further, the natural law does not forbid that which is given simply, to be given for a time or under certain restrictions. Now one unmarried woman may give the power of her body for ever to an unmarried man, so that he may use her when he will. Therefore it is not against the law of nature, if she give him power of her body for a time.
Objection 4: Further, whoever uses his own property as he will, injures no one. But a bondswoman is her master's property. Therefore if her master use her as he will, he injures no one: and consequently it is not against the natural law to have a concubine.
Objection 5: Further, everyone may give his own property to another. Now the wife has power of her husband's body ( 1 Cor. 7:4 ). Therefore if his wife be willing, the husband can have intercourse with another woman without sin.
On the contrary, According to all laws the children born of a concubine are children of shame. But this would not be so unless the union of which they are born were naturally shameful.