Commentary on the Bible, by Adam Clarke, [1831], at sacred-texts.com
The people are commanded to avoid the doings of the Egyptians and Canaanites, Lev 18:1-3. They are to do God's judgments, and to keep his ordinances, that they may live, Lev 18:4, Lev 18:5. Marriages with those who are near of kin are prohibited, Lev 18:6. None to marry with his mother or step-mother, Lev 18:7, Lev 18:8; with his sister or step-sister, Lev 18:9; with his grand-daughter, Lev 18:10; nor with the daughter of his step-mother, Lev 18:11; nor with his aunt, by father or mother, Lev 18:12, Lev 18:13; nor with his uncle's wife, Lev 18:14; nor with his daughter-in-law, Lev 18:15; nor sister-in-law, Lev 18:16; nor with a woman and her daughter, son's daughter, or daughter's daughter, Lev 18:17; nor with two sisters at the same time, Lev 18:18. Several abominations prohibited, Lev 18:19-23, of which the Canaanites, etc., were guilty, and for which they were cast out of the land, Lev 18:24, Lev 18:25. The people are exhorted to avoid these abominations, lest they be treated as the ancient inhabitants of the land were treated, and so cast out, Lev 18:26-28. Threatenings against the disobedient, Lev 18:29, and promises to the obedient, Lev 18:30.
The doings of the land of Egypt - the land of Canaan - The worshipping of demons, beasts, etc., as mentioned in the preceding chapter, Lev 17:7, and the abominations mentioned in this chapter from Lev 18:21-23.
Any that is near of kin - כל שאר בשרו col shear besaro, any remnant of his flesh, i.e., to any particularly allied to his own family, the prohibited degrees in which are specified from the 7th to the 17th verse (Lev 18:7-17) inclusive. Notwithstanding the prohibitions here, it must be evident that in the infancy of the world, persons very near of kin must have been joined in matrimonial alliances; and that even brothers must have matched with their own sisters. This must have been the case in the family of Adam. In these first instances necessity required this; when this necessity no longer existed, the thing became inexpedient and improper for two reasons:
1. That the duties owing by nature to relatives might not be confounded with those of a social or political kind; for could a man be a brother and a husband, a son and a husband, at the same time, and fulfill the duties of both? Impossible.
2. That by intermarrying with other families, the bonds of social compact might be strengthened and extended, so that the love of our neighbor, etc., might at once be felt to be not only a maxim of sound policy, but also a very practicable and easy duty; and thus feuds, divisions, and wars be prevented.
Thy brother's wife - This was an illegal marriage, unless the brother died childless. In that case it was not only lawful for her to marry her brother-in-law, but he was obliged by the law, Deu 25:5, to take her to wife.
A wife to her sister - Thou shalt not marry two sisters at the same time, as Jacob did Rachel and Leah; but there is nothing in this law that rendered it illegal to marry a sister-in-law when her sister was dead; therefore the text says, Thou shalt not take her in her life time, to vex her, alluding probably to the case of the jealousies and vexations which subsisted between Leah and Rachel, and by which the family peace was so often disturbed. Some think that the text may be so understood as also to forbid polygamy.
As long as she is put apart - See Clarke's note on Lev 15:24.
Thy neighbor's wife - See Clarke's note on Exo 20:14.
Pass through the fire to Molech - The name of this idol is mentioned for the first time in this place. As the word מלח molech or melech signifies king or governor, it is very likely that this idol represented the sun; and more particularly as the fire appears to have been so much employed in his worship. There are several opinions concerning the meaning of passing through the fire to Molech.
1. Some think that the semen humanum was offered on the fire to this idol.
2. Others think that the children were actually made a burnt-offering to him.
3. But others suppose the children were not burnt, but only passed through the fire, or between two fires, by way of consecration to him.
That some were actually burnt alive to this idol several scriptures, according to the opinion of commentators, seem strongly to intimate; see among others, Psa 106:38; Jer 7:31, and Eze 23:37-39. That others were only consecrated to his service by passing between two fires the rabbins strongly assert; and if Ahaz had but one son, Hezekiah, (though it is probable he had others, see Ch2 28:3), he is said to have passed through the fire to Molech, Kg2 16:3, yet he succeeded his father in the kingdom, Kg2 18:1, therefore this could only be a consecration, his idolatrous father intending thereby to initiate him early into the service of this demon. See Clarke's note on Lev 20:2.
With mankind - This abominable crime, frequent among the Greeks and Romans as well as the Canaanites, may be punished with death in this country.
With any beast - This abomination is also punishable with death by the laws of this country. Any woman stand before a beast - That this was often done in Egypt there can be no doubt; and we have already seen, from the testimony of Herodotus, that a fact of this kind actually took place while he was in Egypt. See Clarke's note on Lev 17:7, and See Clarke on Lev 20:16 (note).
The land itself vomiteth out her inhabitants - This is a very nervous prosopopoeia or personification; a figure by which any part of inanimate nature may be represented as possessing the passions and reason of man. Here the land is represented as an intelligent being, with a deep and refined sense of moral good and evil: information concerning the abominations of the people is brought to this personified land, with which it is so deeply affected that a nausea is produced, and it vomits out its abominable and accursed inhabitants. It was natural for the inspired penman to make use of such a figure, as the description he was obliged to give of so many and enormous abominations must have affected him nearly in the same way in which he represents the land to be affected.
Shall ye keep mine ordinance - The only way to be preserved from all false worship is seriously to consider and devoutly to observe the ordinances of the true religion. He who in the things of God goes no farther than he can say, Thus it is written, and thus it behoves me to do, is never likely to receive a false creed, nor perform a superstitious act of worship.
1. How true is that word, The law of the Lord is Perfect! In a small compass, and in a most minute detail, it comprises every thing that is calculated to instruct, direct, convince, correct, and fortify the mind of man. Whatever has a tendency to corrupt or injure man, that it forbids; whatever is calculated to comfort him, promote and secure his best interests, that it commands. It takes him in all possible states, views him in all connections, and provides for his present and eternal happiness.
2. As the human soul is polluted and tends to pollution, the great doctrine of the law is holiness to the Lord: this it keeps invariably in view in all its commands, precepts, ordinances, rites, and ceremonies. And how forcibly in all these does it say, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind, and with all thy strength; and thy neighbor as thyself! This is the prominent doctrine of the preceding chapter; and this shall be fulfilled in all them who believe, for Christ is the end of the law for righteousness to them that believe.
Reader, magnify God for his law, for by it is the knowledge of sin; and magnify him for his Gospel, for by this is the cure of sin. Let the law be thy schoolmaster to bring thee to Christ, that thou mayest be justified by faith; and that the righteousness of the law may be fulfilled in thee, and that thou mayest walk, not after the flesh, but after the Spirit.