איש איש אל כל שאר בשרו לא תקרבו; logic would suppose that offspring from genetically related parents would result in superior human beings, evenly matched ones, as for instance in the case of Amram and Yocheved, where the marital union of aunt and nephew produced three outstanding human beings such as Miriam, Aaron, and Moses. In fact, the Talmud Yevamot 62,63 praises someone who marries his niece by quoting Isaiah 58,9 who calls down a special blessing from heaven on such a person. [“Then when you call, the Lord will answer, when you cry, He will say: ‘Here I am.’”] The considerations I have just mentioned are valid only if both parties to such a marital union are motivated exclusively by the desire to carry out G’d’s will as they perceive it. However, truth to tell, this occurs in only rare cases. The vast majority of people, when choosing their mate, are driven by the desire to gratify their libido. Compare Psalms 51,7 הן בעוון חוללתי ובחטא יחמתני אמי, “Indeed, I was born with iniquity; with sin my mother conceived me.” Seeing that genetically close relatives, usually living under the same roof, provide ample opportunity for the males and females of that family to engage in illegitimate sexual relations, and not only do they find it enjoyable but they do not consider it at all sinful, such pairings will hardly ever be for the purpose of marriage, but merely for the purpose of mutual physical indulgence. As a result, allowing marital relations of an incestuous nature would result in sexual promiscuity of major dimensions. This is why the Torah wrote לגלות ערוה, in most instances the very baring of flesh, and especially private parts, is the physical gratification desired in the first instance. This is why the Torah, in order to nip incest in the bud, addresses itself again and again to this phenomenon by using the expression לגלות ערוה, the titillation provided by feasting one’s eyes on the flesh of the opposite sex. When listing degrees of blood relationship, the Torah proceeds from the man’s vantage point, and in the case of the woman from the perspective of her husband. This is why in order of sequence the Torah first forbids the sister of one’s father who is a first degree blood relation to one’s father. On the other hand, the Torah permits the daughter of such father who is a relative of the second degree to the party. The Torah then prohibits the wife of one’s father and the wife of one’s brother and the wife of one’s uncle, even after their respective husbands have already died. This is in spite of the fact that no genetic connection exists between the people forbidden to one another as man and wife. The reason is simply that they Torah views them all from the perspective of how they are related to their husbands. This appears to be the guideline for all incest-related legislation.

זימה היא, it is sexual union based only on lust and sinful intent.

לא תקח לצרור, the Torah means that were it not for the competitive hostility which would result by the two sisters competing for the love of the same man, there would not have been a biological, genetic reason for forbidding such a union. Proof that this is the guiding motivation of the Torah is the fact that after the death of one sister, the surviving husband may marry the surviving sister.

ומזרעך לא תתן להעביר למולך ולא תחלל את שם אלוקיך, the difference between offering sacrifices to the Moloch and to G’d respectively is that to G’d only animals are sacrificed, whereas to the deity known as Moloch, human beings, specifically one’s son, is sacrificed. This would indicate that the worshipper of the Moloch considers him as more powerful than G’d, for why else would he sacrifice his dearest possession, his son, to him and not to G’d?

'אני ה, I have never changed since the time I have sworn to Avraham “to be your G’d and for seed after you.” (Genesis 17,7). Seeing that G’d in this chapter had spoken about incest, matters related to human seed, and His interest in keeping this seed pure so that the holy spirit would be able to descend upon such people, He spoke about the Moloch whose servants had intended to ensure that their other children would be blessed with every kind of success in recognition of their having given the oldest to their G’d. G’d is on record here that doing something like this, far from being a way to sanctifying G’d’s name would be the most potent way to desecrating His name. Such practices, far from attracting the benevolent presence of G’d, the Shechinah, would prevent this presence of G’d from taking up residence among the Jewish people..

אל תטמאו בכל אלה, even by merely being physically close to such incestuous members of the opposite sex.

כי בכל אלה נטמאו הגוים, for the original depravity of the nations dwelling in Canaan before you involved precisely this ritual contamination. They did not start by actually sleeping with the partners outlawed to them, but by only fondling them.

ותטמא הארץ, the next step was that the earth became contaminated by actual incestuous sexual relations between such partners.

ושמרתם אתם את חקותי, not to reveal the nakedness, etc.

ואת משפטי, by punishing the guilty offenders.

ולא תעשו מכל התועבות, by observing these rules you will not become guilty of engaging yourselves in any of these abominable practices.

כי את כל התועבות האל עשו אנשי הארץ, for these nations who did not observe these rules of incestuous sexual mores and who did not punish those who violated these rules, eventually committed all these abominations themselves, proceeding from a relatively minor sin to more serious sins; the same will happen to you if you will be lax in enforcing that these rules be observed, leaving it only to Me to punish the offenders. [it is interesting that the author predicts the outcome of allowing “consenting adults” to choose their own lifestyles. Ed.] This is why I implore you to observe this legislation in all its details.

ולא תקיא הארץ...כאשר קאה את הגוי, and by abstaining from these abominations the land will not spit you out eventually (for other sins) in the same absolute manner in which the people presently in that land are being disgorged by it.

כי כל אשר יעשה מכל התועבות האלה ונכרתו הנפשות, the reason why the land will spit you out if you violate even only part of these laws is that each one is a sufficiently serious violation in My eyes causing the deliberate perpetrator to be punished with the penalty of karet, total separation from the future of the people of the Jewish nation.

ושמרתם את משמרתי לבלתי עשות מחקות התועבות, observe also the legislation which is in the nature of a protective fence against the major sin of indulging in actual sexual relations with the forbidden partners. Just as the legislation governing menstrual laws, eating of forbidden foods, sleeping with a woman ritually impure after giving birth, etc., have all been surrounded with what our sages call a סיג, “protective fence,” this legislation too has such a protective fence which must not be ignored except at your peril. The overriding consideration is לא תטמאו בהם, “do not become spiritually contaminated by ignoring these laws.”