Consider first, that by this commandment is forbidden, in the first place, the heinous crime of adultery, as not only directly contrary to chastity, but to justice also in the highest degree; as carrying with it one of the greatest injuries that can be done to one's neighbour, and violating an indefeasible right, confirmed to him by the law of God and of nature, and withal profaning the sanctity of the matrimonial contract, and breaking through the solemn vows of mutual fidelity annexed to it. But though adultery be the only crime here named, it not being necessary to reckon up in particular all the shameful sins of lust, yet it is not the only evil forbidden by this commandment, which moreover condemns and prohibits all manner of uncleanness, whether committed by or with married persons or single, and much more all other unnatural sins of lust, committed upon one's self, or with any other; as also all abuses of the marriage bed, by any liberties contrary to the sanctity of it, or disagreeable to the end of that holy institution. O how odious are all these impurities in the sight of God and his holy angels, before whose eyes they are committed! What dreadful judgments have they often drawn down from heaven! What black and filthy flames are prepared for the punishment of them in hell! O my soul, let us ever fly and abhor all these abominations!
Consider 2ndly, that by this commandment (as explained by our Lord himself, St. Matt. v. 27, 28, & c.,) are not only forbidden all those grosser sins of uncleanness, but also all other kinds of immodesties which have any manner of tendency towards those greater crimes, even to every wanton glance of the eye, and every impure inclination of the heart. 'You have heard,' said the Lord, 'that it was said to them of old, thou shalt not commit adultery: but i say to you, that whosoever looketh on a woman to lust after her, hath already committed adultery with her in his heart.' If then we would be truly chaste, as the divine law commands us, we must, with holy Job, put a constraint both upon our eyes, and upon our thoughts and imaginations, lest death enter into our souls by those windows. 'I made a covenant,' saith he, 'with my eyes, that I would not so much as think upon a virgin,' Job xxxi. 4, lest, he adds, 'God above should have no part in him.' How much more does this commandment forbid all loose discourse, unchaste words and songs, which not only demonstrate a corrupt heart in them that take delight in talking of such matter, (which St. Paul would not have so much as one named amongst Christians, Eph. v. 3, for 'out of the abundance of the heart the mouth speaketh,' Matt. xii. 34,) but also spread the infection amongst their neighbours, to corrupt them also by filing their minds and hearts with foul imaginations and impure affections? O how common and how dreadful is this evil, and how many souls owe their damnation to it! Ah! it is too true that 'evil communication corrupts good manners;' and that thousands of Christians lose their innocence, and are made a sacrifice to Satan, by means of such lewd discourses and corrupt conversations.
Consider 3rdly, that if this commandment is designed to lay a restraint upon our eyes, upon our thoughts and imaginations, upon our wishes and desires, and upon our words and conversations; how much more upon our actions, by condemning and prohibiting all carnal liberties, all wanton play, all indecent touches, all immodest embraces, & c.: all which violently tend to defile both soul and body with lust. O Christians, deceive not yourselves; all these liberties are criminal, and such as are loudly condemned in the word of God, Gal. v. 19, and Eph. v. 3, 4, as absolutely excluding all that are guilty of them from any inheritance in the kingdom of God.
Conclude, if you desire to have any share in Christ and in his eternal inheritance, to keep your souls and bodies pure from the defilements of lust. In order thereunto, be exact in observing the rule our Lord has given you, Matt. v. 29, 30, viz., of avoiding all occasions that may expose you to the danger of lust, however agreeable or dear they may be to your natural inclinations, or however necessary they may seem to you. For what can be more dear or necessary than a hand or an eye, and yet we must part with these rather than lose our souls. Apply this rule to all such company or conversation, to all such books or entertainments, to all such plays or diversions, to all such shows or comedies, as are apt to fill your mind with impure thoughts, or otherwise to endanger your chastity; and let neither the example, nor the invitations and persuasions, nor the authority of any one living prevail upon you to transgress this divine rule, or to fling yourselves into the jaws of this infernal dragon of lust, which in all such places and occasions lies in wait to devour your souls.