7. Set a watch over your tongue, especially in the presence of the unconverted. "The tongue is a fire, a world of iniquity." David says, "I will keep my mouth with a bridle, while the wicked is before me." I do not mean that you should ever engage in any sinful conversation in the presence of Christians. I know some professors of religion will indulge in senseless garrulity among themselves, and put on an air of seriousness and solemnity before those whom they regard as unconverted. This they pretend to do for the _honor of Christ_. But Christ says, "Out of the abundance of the heart the mouth speaketh." God hates lip service. However, in the company of sinners and formal professors we are peculiarly exposed to temptation, and have need therefore to set a double guard upon our lips. A single unguarded expression from a Christian may do great injury to an unconverted soul. 8. Watch over your heart when engaged in doing good to others. It is then that Satan seeks to stir up pride and vain-glory. 9. Set a _double_ watch over your easily besetting sin. "Let us lay aside every weight, and the sin which doth so easily beset us." Most persons have some constitutional sin, which easily besets them. Satan takes the advantage of this infirmity, to bring us into difficulty. 10. Finally, keep a constant watch over the _imagination_. Since this is the medium through which temptation comes, never suffer your fancy to rove without control. If you mortify this faculty of the soul, it may be a great assistance to your devotion. But, if you let it run at random, you will be led captive by Satan at his will. Strive, then, after a sanctified imagination, that you may make every power of your soul subservient to the glory of God. Your affectionate Brother. LETTER VII. _Self-Denial._ "If any man will come after me, let him deny himself, and take up his cross daily, and follow me."--LUKE 9:23. MY DEAR SISTER,