After divers ceremonial institutions, God here returns to the enforcement of moral precepts. The former are still of use to us as types, the latter still binding as laws. We have here, 1. The sacred authority by which these laws are enacted: I am the Lord your God (Lev 18:1, Lev 18:4, Lev 18:30), and I am the Lord, Lev 18:5, Lev 18:6, Lev 18:21. "The Lord, who has a right to rule all; your God, who has a peculiar right to rule you." Jehovah is the fountain of being, and therefore the fountain of power, whose we are, whom we are bound to serve, and who is able to punish all disobedience. "Your God to whom you have consented, in whom you are happy, to whom you lie under the highest obligations imaginable, and to whom you are accountable." 2. A strict caution to take heed of retaining the relics of the idolatries of Egypt, where they had dwelt, and of receiving the infection of the idolatries of Canaan, whither they were now going, Lev 18:3. Now that God was by Moses teaching them his ordinances there was aliquid dediscendum - something to be unlearned, which they had sucked in with their milk in Egypt, a country noted for idolatry: You shall not do after the doings of the land of Egypt. It would be the greatest absurdity in itself to retain such an affection for their house of bondage as to be governed in their devotions by the usages of it, and the greatest ingratitude to God, who had so wonderfully and graciously delivered them. Nay, as if governed by a spirit of contradiction, they would be in danger, even after they had received these ordinances of God, of admitting the wicked usages of the Canaanites and of inheriting their vices with their land. Of this danger they are here warned, You shall not walk in their ordinances. Such a tyrant is custom that their practices are called ordinances, and they became rivals even with God's ordinances, and God's professing people were in danger of receiving law from them. 3. A solemn charge to them to keep God's judgments, statutes, and ordinances, Lev 18:4, Lev 18:5. To this charge, and many similar ones, David seems to refer in the many prayers and professions he makes relating to God's laws in the 119th Psalm. Observe here, (1.) The great rule of our obedience - God's statutes and judgments. These we must keep to walk therein. We must keep them in our books, and keep them in our hands, that we may practise them in our hearts and lives. Remember God's commandments to do them, Psa 103:18. We must keep in them as our way to travel in, keep to them as our rule to work by, keep them as our treasure, as the apple of our eye, with the utmost care and value. (2.) The great advantage of our obedience: Which if a man do, he shall live in them, that is, "he shall be happy here and hereafter." We have reason to thank God, [1.] That this is still in force as a promise, with a very favourable construction of the condition. If we keep God's commandments in sincerity, though we come short of sinless perfection, we shall find that the way of duty is the way of comfort, and will be the way to happiness. Godliness has the promise of life, Ti1 4:8. Wisdom has said, Keep my commandments and live: and if through the Spirit we mortify the deeds of the body (which are to us as the usages of Egypt were to Israel) we shall live. [2.] That it is not so in force in the nature of a covenant as that the least transgression shall for ever exclude us from this life. The apostle quotes this twice as opposite to the faith which the gospel reveals. It is the description of the righteousness which is by the law, the man that doeth them shall live en autois - in them (Rom 10:5), and is urged to prove that the law is not of faith, Gal 3:12. The alteration which the gospel has made is in the last word: still the man that does them shall live, but not live in them; for the law could not give life, because we could not perfectly keep it; it was weak through the flesh, not in itself; but now the man that does them shall live by the faith of the Son of God. He shall owe his life to the grace of Christ, and not to the merit of his own works; see Gal 3:21, Gal 3:22. The just shall live, but they shall live by faith, by virtue of their union with Christ, who is their life.

These laws relate to the seventh commandment, and, no doubt, are obligatory on us under the gospel, for they are consonant to the very light and law of nature: one of the articles, that of a man's having his father's wife, the apostle speaks of as a sin not so much as named among the Gentiles, Co1 5:1. Though some of the incests here forbidden were practised by some particular persons among the heathen, yet they were disallowed and detested, unless among those nations who had become barbarous, and were quite given up to vile affections. Observe, I. That which is forbidden as to the relations here specified is approaching to them to uncover their nakedness, Lev 18:6. 1. It is chiefly intended to forbid the marrying of any of these relations. Marriage is a divine institution; this and the sabbath, the eldest of all, of equal standing with man upon the earth: it is intended for the comfort of human life, and the decent and honourable propagation of the human race, such as became the dignity of man's nature above that of the beasts. It is honourable in all, and these laws are for the support of the honour of it. It was requisite that a divine ordinance should be subject to divine rules and restraints, especially because it concerns a thing wherein the corrupt nature of man is as apt as in any thing to be wilful and impetuous in its desires, and impatient of check. Yet these prohibitions, besides their being enacted by an incontestable authority, are in themselves highly reasonable and equitable. (1.) By marriage two were to become one flesh, therefore those that before were in a sense one flesh by nature could not, without the greatest absurdity, become one flesh by institution; for the institution was designed to unite those who before were not united. (2.) Marriage puts an equality between husband and wife. "Is she not thy companion taken out of thy side?" Therefore, if those who before were superior and inferior should intermarry (which is the case in most of the instances here laid down), the order of nature would be taken away by a positive institution, which must by no means be allowed. The inequality between master and servant, noble and ignoble, is founded in consent and custom, and there is no harm done if that be taken away by the equality of marriage; but the inequality between parents and children, uncles and nieces, aunts and nephews, either by blood or marriage, is founded in nature, and is therefore perpetual, and cannot without confusion be taken away by the equality of marriage, the institution of which, though ancient, is subsequent to the order of nature. (3.) No relations that are equals are forbidden, except brothers and sisters, by the whole blood or half blood, or by marriage; and in this there is not the same natural absurdity as in the former, for Adam's sons must of necessity have married their own sisters; but it was requisite that it should be made by a positive law unlawful and detestable, for the preventing of sinful familiarities between those that in the days of their youth are supposed to live in a house together, and yet cannot intermarry without defeating one of the intentions of marriage, which is the enlargement of friendship and interest. If every man married his own sister (as they would be apt to do from generation to generation if it were lawful), each family would be a world to itself, and it would be forgotten that we are members one of another. It is certain that this has always been looked upon by the more sober heathen as a most infamous and abominable thing; and those who had not this law yet were herein a law to themselves. The making use of the ordinance of marriage for the patronizing of incestuous mixtures is so far from justifying them, or extenuating their guilt, that it adds the guilt of profaning an ordinance of God, and prostituting that to the vilest of purposes which was instituted for the noblest ends. But, 2. Uncleanness, committed with any of these relations out of marriage, is likewise, without doubt, forbidden here, and no less intended than the former: as also all lascivious carriage, wanton dalliance, and every thing that has the appearance of this evil. Relations must love one another, and are to have free and familiar converse with each other, but it must be with all purity; and the less it is suspected of evil by others the more care ought the persons themselves to take that Satan do not get advantage against them, for he is a very subtle enemy, and seeks all occasions against us. II. The relations forbidden are most of them plainly described; and it is generally laid down as a rule that what relations of a man's own he is bound up from marrying the same relations of his wife he is likewise forbidden to marry, for they two are one. That law which forbids marrying a brother's wife (Lev 18:16) had an exception peculiar to the Jewish state, that, if a man died without issue, his brother or next of kin should marry the widow, and raise up seed to the deceased (Deu 25:5), for reasons which held good only in that commonwealth; and therefore now that those reasons have ceased the exception ceases, and the law is in force, that a man must in no case marry his brother's widow. That article (Lev 18:18) which forbids a man to take a wife to her sister supposes a connivance at polygamy, as some other laws then did (Exo 21:10; Deu 21:15), but forbids a man's marrying two sisters, as Jacob did, because between those who had before been equal there would be apt to arise greater jealousies and animosities than between wives that were not so nearly related. If the sister of the wife be taken for the concubine, or secondary wife, nothing can be more vexing in her life, or as long as she lives.