The case of a connection with both a woman and her daughter or granddaughter is next mentioned (ver. 17); and, with special emphasis, is declared to be "wickedness," or "enormity."
The prohibition (ver. 18) of marriage with a sister-in-law, as is well known, has been, and still is, the occasion of much controversy, into which it is not necessary here to enter at length. But, whatever may be thought for other reasons as to the lawfulness of such a union, it truly seems quite singular that this verse should ever have been cited as prohibiting such an alliance. No words could well be more explicit than those which we have here, in limiting the application of the prohibition to the life-time of the wife: "Thou shalt not take a woman to her sister, _to be a rival to her_, to uncover her nakedness, beside the other _in her life time_" (R.V.). The law therefore does not touch the question for which it is so often cited, but was evidently only intended as a restriction on prevalent polygamy. Polygamy is ever likely to produce jealousies and heart-burnings; but it is plain that this phase of the evil would reach its most extreme and odious expression when the new and rival wife was a sister to the one already married; when it would practically annul sisterly love, and give rise to such painful and peculiarly humiliating dissensions as we read of between the sisters Leah and Rachel. The sense of the passage is so plain, that we are told that this interpretation "stood its ground unchallenged from the third century B.C. to the middle of the sixteenth century _A.D._" Whatever opinion any may hold therefore as to the expediency, upon other grounds, of this much debated alliance, this passage, certainly, cannot be fairly cited as forbidding it; but is far more naturally understood as by natural implication permitting the union, after the decease of the first wife. The laws concerning incest therefore terminate with ver. 17; and ver. 18, according to this interpretation, must be regarded as a restriction upon polygamous connections, as ver. 19 is upon the rights of marriage.
It seems somewhat surprising that the question should have been raised, even theoretically, whether the Mosaic law, as regards the degrees of affinity prohibited in marriage, is of permanent authority. The reasons for these prohibitions, wherever given, are as valid now as then; for the simple reason that they are grounded fundamentally in a matter of fact,--namely, the nature of the relation between husband and wife, whereby they become "one flesh," implied in such phraseology as we find in ver. 16; and also the relation of blood between members of the same family, as in vv. 10, etc. Happily, however, whatever theory any may have held, the Church in all ages has practically recognised every one of these prohibitions, as binding on all persons; and has rather been inclined to err, if at all, by extending, through inference and analogy, the prohibited degrees even beyond the Mosaic code. So much, however, by way of guarding against excess in such inferential extensions of the law, we must certainly say: according to the law itself, as further applied in chap. xxi. 1-4, and limited in Deut. xxv. 5-10, relationship by marriage is not to be regarded as precisely equivalent in degree of affinity to relationship by blood. We cannot, for instance, conceive that, under any circumstances, the prohibition of the marriage of brothers and sisters should have had any exception; and yet, as we have seen, the marriage between brother and sister-in-law is explicitly authorised, in the case of the levirate marriage, and by implication allowed in other cases, by the language of ver. 18 of this chapter.
But in these days, when there is such a manifest inclination in Christendom, as especially in the United States and in France, to ignore the law of God in regard to marriage and divorce, and regulate these instead by a majority vote, it assuredly becomes peculiarly imperative that, as Christians, we exercise a holy jealousy for the honour of God and the sanctity of the family, and ever refuse to allow a majority vote any authority in these matters, where it contravenes the law of God. While we must observe caution that in these things we lay no burden on the conscience of any, which God has not first placed there, we must insist--all the more strenuously because of the universal tendency to license--upon the strict observance of all that is either explicitly taught or by necessary implication involved in the teachings of God's Word upon this question. Nothing more fundamentally concerns the well-being of society than the relation of the man and the woman in the constitution of the family; and while, unfortunately, in our modern democratic communities, the Church may not be able always to control and determine the civil law in these matters, she can at least utterly refuse any compromise where the civil law ignores what God has spoken; and with unwavering firmness deny her sanction, in any way, to any connection between a man and a woman which is not according to the revealed will of God, as set before us in this most holy, good, and beneficent law.