And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,)
full of grace and truth.
—John 1.14.



Thomas Boston
Minister of the Gospel at Ettrick, Scotland

excerpted from his

on the
Shorter Catechism

EXOD. 20.14.—Thou shalt not commit adultery.

THE scope of this command is the preservation of our own and our neighbour's chastity and purity. God is a holy God, and the devil is an unclean spirit: we must therefore study purity in all manner of conversation. Our Lord puts this command before the sixth, Mark 10.19, because our chastity should be as dear to us as our life, and we should be as much afraid of that which defiles the body as that which destroys it.

This command is a negative precept, and expressly forbids adultery: but under that is comprehended all manner of uncleanness whatsoever, with all the causes and occasions leading thereunto. And the positive part of this command is, that we must preserve our own and our neighbour's chastity by all due means.

In discoursing further, I shall consider,

I. The duties required in this command.

II. The sins forbidden therein.

III. Make some practical improvement.

I. Our first business is to consider what is required in this command; and the Catechism, agreeably to holy scripture, tells us, that it requires 'the preservation of our own and our neighbour's chastity in heart, speech, and behaviour.'

The duties of this command may therefore be reduced to two general heads. (1.) The preservation of our own chastity. (2.) The preservation of that of our neighbour.

FIRST, This command requires us to preserve our own chastity and purity. There is a twofold chastity. 1. In single life; when it is led in purity, it is like the angelical; when in impurity, it is devilish. 2. There is conjugal chastity, when married persons keep themselves within the bounds of the law of that state. This lies in two things. (1.) With respect to all others, keeping themselves pure and uncorrupted. (2.) With respect to another, keeping themselves within the bounds of Christian sobriety and moderation. In whatsoever state we are, 'this is the will of God, even our sanctification, that we should abstain from fornication; that every one of us should know how to possess his vessel in sanctification and honour, not in the lust of concupiscence,' 1 Thess. 4.3-5.

Now, there is a threefold chastity required of us, and to be preserved by us.

First, Chastity in heart, 1 Thess. 4.5, forecited. God knows the heart, and therefore his laws reach the heart, and he will judge for heart-sins. We must keep our minds pure, that the thoughts be not led astray and corrupted. Hence Job 'made a covenant with his eyes,' chap. 31.1. And we must keep our affections pure, that they be not vitiated. Job saw this when he appeals to God, 'If mine heart have been deceived by a woman,' verse 9. This is to be pure before God, who seeth in secret, and searcheth the hidden things of darkness. The least glance over this hedge is a crime.

Secondly, Chastity of speech, Col. 4.6, 'Let your speech be always with grace, seasoned with salt.' As there is tongue-murder, there is tongue-adultery. But our speeches must savour of sobriety and purity: and so they will, if the heart be pure; for out of the abundance of the heart the mouth speaketh. The Holy Ghost, in the scriptures, gives us a pattern to be imitated in our speeches concerning those things that have a natural turpitude with them, vailing the same in modest expressions.

Thirdly, Chastity in behaviour, which comprehends both the keeping of the body undefiled by any gross act, and a modest carriage every way, 1 Pet. 3.2. Modesty must appear in the whole of our behaviour, that the purity of the heart may shine forth thereby, as the candle gives light through the lanthorn.

Now, as this threefold chastity is required here, so the proper means for preserving it are also required.

1. Watching over our senses. These are the ports at which Satan breaks in, and ruins people's purity. The heart and the senses are like a candle-wick, at the end of which lies a heap of powder. Objects set fire to the senses at the wick, and these carry it along to the heart where the corruption lies as a heap of powder. Particularly,

(1.) The eyes, Job 31.1. These were the gates at which sin first entered into the world; and these have been the gates of destruction to many, whereby their fame, body, and souls, have been destroyed together. It is remarkable that the Sodomites were smitten with blindness, who took so little care to watch their eyes while they had the use of them. Curious glances of the eye have been fatal to many, as to David, 2 Sam. 11.2, and to Joseph's mistress, Gen. 39.7.

(2.) The ears. The corruption of the heart makes people liable to be chained with Satan's fetters by the ears as well as the eyes; as appears from Prov. 7.21,22. 'With her much fair speech she caused him to yield, with the flattering of her lips she forced him. He goeth after her straightway, as an ox goeth to the slaughter, or as a fool to the correction of the stocks.' And curious listening to rotten speeches, or whatsoever has a tendency to corrupt the heart is to open a door to let out our purity.

2. Temperance, a sober use of meat, drink, sleep, and recreations. Hence our Lord warns his disciples, Luke 21.34, 'Take heed to yourselves, lest at any time your hearts be overcharged with surfeiting and drunkenness.' Temperance is a necessary hedge for chastity, and the breaking over that hedge is a near way to sacrifice the other. See Acts 24.24,25, 'And, after certain days, when Felix came with his wife Drusilla, which was a Jewess, he sent for Paul, and heard him concerning the faith in Christ.—And as he reasoned of righteousness, temperance, and judgment to come, Felix trembled.' Why did the apostle chuse that subject before these great persons? Why, truly it was very fit. Historians tell us, that this Drusilla was a most libidinous woman, and had left her husband, Aziz king of Emenessa; and while he was yet living, she was married to Felix, who was taken with her beauty; and so they lived together in adultery. The body being pampered becomes a luxuriant beast; and those that cram their bellies with meat and drink, are but one remove from, and in near disposition to filthiness; for one sensuality makes way for another.

On this account it is that fasting and prayer may be to people a duty of this command; for, as some devils are not cast out, so some are not held out but by fasting and prayer. They that would keep themselves pure, must have their bodies in subjection, and that may require, in some cases, a holy violence, 1 Cor. 9.27.

3. Keeping of chaste and modest company. Hence Solomon exhorts, Prov. 5.8,9, 'Remove thy way far from her, and come not nigh the door of her house: lest thou give thine honour unto others, and thy years unto the cruel.' How many have been ruined by the company they have fallen into, worse than they had fallen into a den of lions and wolves! Ill company wears off insensibly the impressions of virtue on people's spirits; and if they be not at war with them, the maintaining of peace and converse will make people like them.

4. Being busied in some honest employment. Those that would be virtuous indeed, must not eat the bread of idleness. Honest labour and business cuts off many temptations that idle persons are liable to. Had David been in the field with his army, when he was rising from off his bed in the evening-tide, 2 Sam. 11.2, he had preserved his chastity when he lost it, and so had Dinah, if she had been at her business in her father's house, when she went out to see the daughters of the land, Gen. 34.1.

5. Marriage, by those that have not the gift of continency. Hence says the apostle, 1 Cor. 7.2,9, 'To avoid fornication, let every man have his own wife, and let every woman have her own husband. But if they cannot contain, let them marry: for it is better to marry than to burn.'—Neither marriage nor single life are in themselves morally good or evil, but indifferent. But that state of life is to be chosen by every one, that will most conduce to their leading a holy life. So every particular person ought by themselves to ponder their gift, and other circumstances, which will let them see what is sin and what is duty in this case.

6. Cohabitation and conjugal love and affection betwixt married persons, without which that state will be no fence to purity, but a snare. Hence Solomon says, Prov. 5.19,20, 'Let her be as the loving hind, and pleasant roe; let her breasts satisfy thee at all times, and be thou ravished always with her love. And why wilt thou, my son, be ravished with a strange woman, and embrace the bosom of a stranger?'

7. Lastly, Shunning all occasions, and resisting all temptations, to the contrary, Prov. 5.8, forecited. So did Joseph, Gen. 39.8. It is a dangerous business to parley with them. The town that is content to capitulate with the enemy, is next door to surrendering. There are two sins that the scripture bids us flee from. (1.) Idolatry, 1 Cor. 10.14. (2.) Uncleanness, 1 Cor. 6.13. Why? Because they are bewitching evils. It is safer to flee, than to stand to fight them.

SECONDLY, This command requires us to preserve the chastity of others, and that so far as we can, in their hearts, lips, and lives. For so far as we might prevent the sin of others, and do it not, and much more when we occasion it, it becomes ours. Besides, that in preserving our own chastity, we preserve that of others, and so the means conducing to the one do also conduce to the other. Our duty in this point may be reduced to these two heads.

1. That we may do nothing which may ensnare others. For whosoever lays the snare is partner in the sin that comes by it. A lamentable instance of this we have in Judah and his daughter-in-law: they were neither of them careful to preserve the other's chastity, and so they fell each by another's snare, Gen. 38.14-16. For this cause modest apparel is here required, 1 Tim. 2.9: and a careful avoiding of all unseemly behaviour, which may have a tendency to defile the minds of others, though we ourselves have no ill intention. Thus, Bathsheba's washing herself in a place where she might be seen of others, was the sad occasion of the sin that David and she were plunged into, 2 Sam. 11.2. And truly where both grace and good manners are wanting, it is little wonder that people break their necks over one another.

2. That we do every thing incumbent on us to preserve the chastity of others, in heart, speech, and behaviour. Let married persons live together in due love and affection to one another. Let each one be an example of purity to others. Let those whom ye see in danger be rescued by all means, whether by force or persuasion, as the circumstances require. And let none bring others' guilt on their own heads, by being silent when they see the smoke, till the flame rise and discover itself. Let parents and masters do what they can to prevent the ruin of their children and servants, by rebuking any lightness about them, exhorting them, and praying for them; keeping them out of ill company, not suffering them to be idle or vague, and seasonably disposing of children in marriage. Our bodies are the Lord's; we are or ought to be the temples of God; the heart is the most holy place of the temple, and our speech and behaviour the holy place. Let us take heed we bring in no unclean thing there, but keep his temple pure; for if any defile the temple of God, him will God destroy.

II. I come now to shew, what is forbidden in this command. It forbids 'all unchaste thoughts, words, and actions.'

In nothing more quickly did the corrupt nature of man vent itself, than in inordinate concupiscence, which brought shame along with it, as its just punishment; which makes it hard to speak of it, and so much the rather that corrupt nature is apt, through Satan's influence, to turn the very commandment against it into an occasion of sin. Therefore, though there is a necessity of speaking something on it, we cannot enlarge with that freedom upon it that we can do on other commands. Sift your hearts, then, as in the presence of a holy God, who will call us to an account in this matter before his tremendous judgment-seat, and hear his holy law, Thou shalt not commit adultery.

In this short abbreviate of the law of God, where one sin is expressly condemned, under it are forbidden all sins of the same kind. So here the whole dunghill of filthiness is set before us for our abhorrence, and detestation of our souls, as we would not bring down the wrath of God on us. Here then all gross acts are forbidden. As,

1. All unnatural lusts, not to be mentioned without horror; filthy fellowship with devils, as the guilty do suppose; Sodomy, persons abusing themselves with those of their own sex, Rom. 1.24-27; beastiality, Lev. 18.22; And to these we may add incest, which is betwixt persons within the forbidden degrees of consanguinity or affinity, Lev. 18.6. Concerning which this is to be observed, that a man must hold at the same distance from the relations of his wife as his own, and contrariwise, Lev. 20.14; and such unnatural mixtures can never be sanctified by marriage.

2. Adultery, where one of the parties, or both are married. In this case the aggravations of the sin of the married party will be justly charged upon the single person; and for both, 'whoremongers and adulterers God will judge,' Heb. 13.14. And bigamy and polygamy are adultery; for the vile fact cannot be sanctified, but made worse, by marriage with the adulterer or adulteress, Hos. 410; 'They shall commit whoredom, and shall increase.'

3. Fornication, which is betwixt single persons, Col. 3.5,6, 'Mortify your members which are upon the earth; fornication, uncleanness, &c. For which thing's sake the wrath of God cometh upon the children of disobedience.' Whoredom is a sin that without repentance is a sad badge of a subject of Satan, Eph. 5.5. 'No whoremonger nor unclean person—hath any inheritance in the kingdom of God and Christ.' And a vast inconsistency there is betwixt being a member of Christ, and that of a harlot, 1 Cor. 6.15.

4. Rape, or forcing a person to filthiness, Deut. 22.25. This is a capital crime by the laws of God and men.

5. Secret uncleanness in a person by themselves alone, whether they be waking, Eph. 5.12; or sleeping, at least so far as they have occasioned it to themselves by their own corrupt imaginations.

6. Lastly, Immoderate and unseasonable use even of the mar-riage-bed, and much more of the bed of whoredom. Mark these passages, 1 Thess. 4.3,4. 1 Cor. 7.5. Isa. 58.13. Ezek. 22.10. and 18.6.

These are the several kinds of vileness here forbidden. But this command goes further, and forbids three sorts of uncleanness besides.

1. Uncleanness in heart, all speculative filthiness, unclean imaginations, thoughts, purposes, and affections, though people do not intend to pursue them to the gross act, Matt. 5.28; 'Whosoever looketh on a woman to lust after her, hath committed adultery with her already in his heart.' Chap. 15.19; 'Out of the heart proceed—adulteries, fornications.' These fall not under the eye of men, but are open to the eye of God, who will judge accordingly. A voluntary thought of these things is dangerous, a delightful rolling of them in the heart is uncleanness before God, and a vitiated habit, whereby on every light occasion these filthy sparks are kindled in the heart, is worst of all, and most abominable.

2. Uncleanness in words, all filthy communications and obscene language, Eph. 4.29; 'Let no corrupt communications proceed out of your mouth.' They are the discoveries of a filthy heart; for 'out of the abundance of the heart the mouth speaketh,' contrary to nature, propaling those things which nature teaches to keep secret. They are snares to the hearers; and to speak of them for delight is to act the filthiness in words, when they cannot do it otherwise. Neither will the art some have in dressing up their filthy notions in figurative terms excuse; but these in some sort are most dangerous, because the devilish wit displayed in them makes them more sticking; and so by means of the like phrases occurring in holy exercises, they are the readier even to defile these. Of this sort are filthy songs and ballad singing; and the delightful listening to such things, as the simple youth did to the speeches of the adulterous whore, Prov. 7.18-21.

3. Uncleanness in actions. Besides the gross acts, there are others leading thereunto, which are there also forbidden. As,

(1.) Wanton looks: there are 'eyes full of adultery,' 2 Pet. 2.14; 'wanton eyes,' Isa. 3.16; even a look for unlawful carnal delight is the venting of the impurity of the heart; and though it be only from levity and curiosity, it is sinful, as a mean leading to evil.

(2.) Impudent and light behaviour, and immodest gestures, Isa. 3.16.; indecent postures, contrary to religion and good manners. These are hellish matters of sport, that defile the actors, and those that are witnesses to them without abhorrence. And on this ground stage-plays and filthy pictures are amongst the things forbidden in this command, Ezek. 23.14-16.

(3.) Luxurious embraces and dalliances. These are as smoke going before the flame, and were practised by the adulterous whore, Prov. 7.13.

Now, as all these are here forbidden, so all occasions and incentives to lust are forbidden, all that has a tendency to corrupt our own or neighbour's chastity.

(1.) Immodest apparel, Prov. 7.10. God appointed apparel: [1.] For necessity, to cover our shame and nakedness; [2.] To distinguish sexes; [3.] To distinguish callings, the more noble from the meaner sort. The devil has found out the fourth, to be enticements to lust.

(2.) Keeping ill company. This has been the ruin of many: therefore Solomon advises, Prov. 5.8, 'Remove thy way far from her,' a strange woman or whore; 'and come not nigh the door of her house.' It was Joseph's commendation that he fled from his mistress. Whatever the company be, people should beware that they cast not themselves into snares.

(3.) Idleness, the nursery of all filthiness, Ezek. 16.49. This exposeth to many temptations; for Satan will be ready to find idle people work. Gadding and vaguing abroad can hardly miss to have an unsavoury end.

(4.) Intemperance, gluttony, and drunkenness. These have a tendency to murder, which is forbidden in the sixth command, and to uncleanness, forbidden in the one under consideration, Prov. 23.30,31,33. Notable to this purpose is that scripture, Jer. 5.8; 'They were as fed horses in the morning: every one neighed after his neighbour's wife.

(5.) Promiscuous dancing, or dancing of men and women together. This entertainment, however reckoned innocent among many, is evidently an incentive to lust, Isa. 23.15-17. It is supposed, that it was to a dancing match among the daughters of the land that Dinah went forth, when she was dealt with as an harlot. This practice seems to be struck at by these scriptures, Rom. 13.13; 'Let us walk—not in chambering and wantonness,' 1 Pet. 4.3, where mention is made of 'walking in revelling.' It is offensive to the grave and pious, is condemned by our church, yea, and has been condemned by some sober heathens.

(6.) Undue delay of marriage, 1 Cor. 7.7-9; for they that refuse the remedy, strengthen the disease.

(7.) Unjust divorce, Matth. 5.32; wilful desertion, 1 Cor. 7.12,13; want [lack] of conjugal affection, and all harshness and unkindness betwixt married persons. These are to be avoided as incitements to uncleanness.

(8.) Lastly, The popish doctrine and practice of forbidding lawful marriages, 1 Tim. 4.3; dispensing with unlawful marriages, Mark 6.18; tolerating of stews or bawdy houses, Deut. 23.17; and entangling vows of single life, Mark 19.10,11.

I shall next make some improvement of this subject.

1. Let those that have fallen into the sin of uncleanness, repent, and walk humbly all the days of their life under the sense of it. There are, alas! not a few amongst us to whom this exhortation belongs. And perhaps, if their eyes were opened, they would see something in their lot that God has sent to go along with them, as a mark of his displeasure against that their sin; wherein they might with no great difficulty read their old sin in a continued punishment. That sin may be forgotten with us, that is not so with the Lord.

2. Let those that stand take heed lest they fall. Labour to get your hearts possessed with a dread of this sin, and watch against it, especially ye that are young people, seeing it is a sin most incident to youth when the passions are most vigorous; which yet may stick fast with the blue marks of God's displeasure upon you when you come to age. For motives, consider,

(1.) It is not only a sin, but ordinarily, if not always a plague and punishment for other sins. It is a mark of God's anger against the person that is permitted to fall into it, Prov. 22.14. 'The mouth of a strange woman is a deep pit: he that is abhorred of the Lord, shall fall therein.' This is a heavy mark of God's indignation, which is worse than to fall into a fever, or some lingering distemper; for a person may recover of these in a short time, but it is not so easy to recover the other.

(2.) It is a sin that very few ever get grace to repent of. It stupefies the conscience, and wastes all sense of sin from it, Hos. 4.11. I have seen, alas! too many that have made public satisfaction for that sin; but allow me to say, I have seen very few by whose repentance I was much edified. Hear what the Spirit of God says of these unhappy people, Prov. 2.19, 'None that go unto her, return again, neither take they hold of the paths of life.' None, that is, very few; but some indeed do, as among the Corinthians, 1 Cor. 6.9,11. And be not offended, but cautioned, if I say, that few women particularly ever get grace to repent of it. Solomon said it before me, Eccl. 7.28, 'A woman among all those have I not found.' And observe what is said, Acts 24.25, that Felix trembled when Paul preached, though he repented not; but there is not a word of Drusilla's being moved.

(3.) It dishonours and debases the body, 1 Cor. 6.18, Our bodies are the members of Christ or should be; but how are they debased, being made members of an harlot? And how low and contemptible a thing is such a wretched creature, even in the eyes of those that join with them?

(4.) It leaves an indelible stain upon their reputation; their honour is sunk, and there is no recovering of it, Prov. 6.33. Though the sin may be pardoned before God, yet the blot lies on their name, while they have a name on the earth. Yea, and when they are dead and gone, their bastard posterity still lie under the stain, whereof they could be no cause.

(5.) Poverty and want oft-times follow it. It natively tends to poverty, Prov. 5.10. and there is a secret curse of that nature that often accompanies it, Prov. 6.26, 'By means of a whorish woman a man is brought to a piece of bread.' How many have been made miserable by it, who have had occasion as long as they lived to remember they had ruined themselves?

(6.) Lastly, It is ruining to the soul, Prov. 6.32, 'He that doth it,' commit adultery with a woman, 'destroyeth his own soul.' It ruins it here, in so far as it defiles the conscience, fetters the affections, blinds the mind, utterly unfits for communion with God, till the guilt be washed off by the application of Christ's blood, after a frightful awakening of the conscience. And if they do not repent of this sin, it will destroy the soul for ever. Let these scriptures imprint a horror of it on the minds of all, Heb. 13.4; 1 Cor. 6.9; Gal. 5.19,21; Rev. 21.8.

I close with a few directions in so many words.

1. Give yourselves away soul and body to Jesus Christ, and learn to live by faith, sensible of your own weakness, and relying on his promised strength; for without him ye can resist no sin, nor temptation to sin.

2. Beware of a carnal frame of sloth and laziness. Labour to be spiritual and heavenly in the frame of heart, Gal. 5.16, 'Walk in the Spirit, and ye shall not fulfil the lust of the flesh.'

3. Watch over your heart and senses. Make a covenant with your eyes, as Job did, that ye may avoid unlawful looks; and never venture on the devil's ground, otherwise ye will fall into the snare.

4. Study mortification of all your unruly lusts and passions, and beware of all occasions and incentives to this wickedness.

5. Keep at a distance from immodest company, and be not too frolicsome and foolish, light and airy in your discourse.

6. Lastly, Pray fervently and importunately, that the Lord may save you from this foul sin, and all temptations to it; saying with David, Psalm 119.37. 'Turn away mine eyes from beholding vanity.'