Comentario sobre Levítico 18:6

לא תקרבו NONE OF YOU SHALL APPROACH TO [ANY THAT IS NEAR OF KIN TO HIM] — The intention is to admonish women as well as men (in respect to this general prohibition of unchastity); on this account the plural is used (Sifra, Acharei Mot, Chapter 13 1).

NONE OF YOU SHALL APPROACH TO ANY THAT IS NEAR OF KIN TO HIM, TO UNCOVER THEIR NAKEDNESS. The reason for the prohibition of sexual relationships with one’s near of kin is not expressly written [in the Torah]. The Rabbi [Moshe ben Maimon] wrote in the Moreh Nebuchim²⁵³Guide of the Perplexed III, 49. that [this law seeks to inculcate the lessons that] we should limit sexual intercourse, hold it in contempt, and perform it rarely. Now these women which Scripture has forbidden amongst the relatives of one’s wife are forbidden because they are constantly together with him in his house,²⁵⁴“For as a rule, the mother of the wife, her grandmother, daughter, granddaughter, and sister-in-law are often with her; the husband meets them always when he goes out, when he comes in, and when he is at his work” (ibid., Friedlander’s translation). Now “if we were allowed to marry any of them, and were only precluded from sexual intercourse with them without marriage, most people would constantly become guilty of misconduct with them. But as they are entirely forbidden to us … there is reason to expect that people will not seek it, and will not think of it” (ibid.). and the same applies to one’s own relatives [sisters, aunts, and the wife of one’s uncle], who are frequently with him and he is closeted together with them. A similar reason the Rabbi states for all forbidden relations. Now Rabbi Abraham ibn Ezra has already written²⁵⁵In the verse before us. likewise that since the passion of man’s heart is like that of the animals, it was impossible for Scripture to forbid all females, and therefore it prohibited only those that are available to him at all times. But this is a very weak reason, that Scripture should make a person liable to the punishment of excision in the case of these forbidden relations, just because they are sometimes found together with him, and at the same time permit a man to marry many women, even in the hundreds and thousands! And what harm would there be if a man would marry only his daughter, just as was permitted to the Noachides,²⁵⁶Sanhedrin 58 b. or marry two sisters as did our patriarch Jacob? A person also could not do better than to give his daughter in marriage to his elder son, and they would inherit his possessions and multiply and increase in his house, for He created not the earth a waste, He formed it to be inhabited!²⁵⁷Isaiah 45:18. We have no tradition as to [the reason of] this prohibition of forbidden relationships, but logically it would appear that there is in this matter one of the secrets of creation, which attaches to the soul and is part of the secret of the transmigration [of souls], to which we have already alluded.²⁵⁸Genesis 38:8 (Vol. I, pp. 469-470).
Know that sexual intercourse is held distant and in contempt in the Torah unless it is for the preservation of the human species, and therefore where there can be no offspring [such as in pederasty or carnal intercourse with beasts], it is forbidden. Similarly, where [the union is such that] the child born therefrom will not have a healthy existence, nor succeed from it, the Torah prohibited such a union. This is the sense of the expressions: el kol ‘sh’eir’ b’saro [literally: to any ‘flesh’ next to his flesh]; for he hath made naked ‘eth sh’eiro’²⁵⁹Further, 29:19. See Ramban on Exodus 21:9 (Vol. II, pp. 356-7), where he elaborates on the meaning of this word sh’eir. [literally: his flesh]. Thus the Torah forbade these marriages on account of sh’eir [i.e., because the forbidden relations constitute “flesh” next to one’s own], the term sh’eir being derived from the expression [in the verse], ‘hanish’ar’ (he that is left) in Zion, and he that remaineth in Jerusalem.²⁶⁰Isaiah 4:3. The term sh’eir denoting “flesh” or “relative” is something which “remains” with a person, as it is his own or next to his flesh. Hence Scripture states, they are ‘sha’arah’ (near kinswomen); it is lewdness,²⁶¹Further, Verse 17. meaning to say, “these are not marriages, nor fit for such a relationship, for they will not succeed [in having healthy offspring, as explained above]; rather it is lewdness, mere thoughts of indecency.” Thus the forbidden relationships are included in “the statutes,” the laws which constitute “the decrees of the King.” Now a decree is an ordinance which originates in the knowledge of the King, Who is wise in the management of His kingdom, and it is He Who knows the need for and the benefit of the command that He ordained, and He does not tell it to anyone except to His wise counsellors.

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.

איש איש אל כל-שאר בשרו, ”any man shall not approach his close relative, etc.” Nachmanides writes that the underlying reason for the legislation not to indulge in incestuous relationships has not been spelled out in the Torah. Maimonides claims in his Guide for the Perplexed (3,49) that the underlying reason is to minimize the frequency of indulging one’s libido, and with close relatives who may live in the same house such opportunities exist more than with potential sexual partners who live elsewhere. The subject is closely related to matters discussed in the Sefer Yetzirah, that the author claims not to have understood. Moreover the subject of sexual gratification contains animalistic elements at the same time as the fulfillment of the first commandment G’d gave man. Anyone who knows that in indulging his libido he will not or cannot fulfill that commandment must not indulge in sexual intercourse. Seeing that in order to fulfill the commandment to multiply, i.e. to have children, our libido has its positive part to play in the way the Creator arranged the human race, it was impossible to outlaw sexual activity altogether. He therefore legislated what from our vantage point may look like a compromise, but what from His vantage point no doubt reflects His superior wisdom. [Some of this wording is my own. Ed.]

In plural form. You might ask: It is normal for verses to speak in the plural form, which means each one of you as [above] where it says תשמרו, לא תעשו, and לא תלכו? The answer is: Here it is different, because at the beginning it is written in the singular, “each and every person,” and afterwards it is written תקרבוin the plural form. Perforce תקרבו comes to include females. You might ask: Why does the verse have to [specially] include [females] regarding prohibited relationships, which is a negative commandment, for females too are obligated to keep negative commandments since they are compared to men regarding all punishments of the Torah as the Gemara says in Kidushin (35a). The answer is: Prohibited relationships are different because regarding other prohibitions of the Torah such as forbidden foods of נבילה and טריפה, it is logical that a woman is liable because she violates the prohibition the same manner a man does. But regarding prohibited relationships, the man is the active party whereas the woman does nothing for she is [as passive] as the earth. Therefore, the Torah needs to include that she too is liable.

לא תקרבו, “do not approach;” this expression is a simile for describing carnal relations. An example of the use of this expression elsewhere is in Genesis 20,4: ואבימלך לא קרב אליה, “Avimelech did not approach her,” or Isaiah 8,3: ואקרב אל הנביאה, “I was intimate with the prophetess;”

'אני ה I AM THE LORD, who am faithful to pay you your reward (Sifra, Acharei Mot, Chapter 13 13.

Faithful to give a reward. Even though here there is no performance of a mitzvah but only keeping away from a sin, and the giving of a reward is only appropriate regarding to an action, one may say that if a person had opportunity to sin and refrained himself from sinning, he is rewarded as if he performed a mitzvah, as we find in Kidushin 39b.

לא תקרבו, the reason this line is used in the plural mode is to warn both parties not to indulge in such carnal relations. The normally more passive partner is considered equally guilty.