+I. The Divine law as a lamp.+ 1. _It is like a lamp because it is portable._ A light that cannot be carried from place to place will be useless to a man who has to find his way home in the dark on an uneven road. Life is such a journey, and the commandment of the Lord can be carried in man's memory and heart: "Thy Word have I hid in mine heart, that I might not sin against Thee" (Psa. cxix. 11). 2. _Its existence declares that men need light from a source outside themselves._ A man's eyes on a dark night are not sufficient to enable him to find the right road. If he depends simply upon them he will find that the "light within him is darkness" (Luke xi. 35). He must have external help. The existence of God's revelation in the world proves that man has not enough light within him to guide his feet into the way of peace. His own spiritual perception will not enable him to find his way through the night to eternal day. 3. _It is in constant requisition._ The position and relation of our globe to the sun makes it certain that night will constantly succeed the day. And while the night continues to follow day the lamp will be needed to illumine the darkness. The Divine lamp will never be out of use while temptation, and doubt, and sin, and ignorance beset the path of man, as certainly as the revolution of the globe brings the night. +II. The commandment as a guide.+ "When thou goest, it shall lead thee" (verse 22). Where leading is promised ignorance is implied. The man who trusts to another to guide him acknowledges by the act that the guide knows more than he does. Scripture takes for granted that man is ignorant. Its existence implies that man needs information and direction concerning his life. +III. The commandment as a guard.+ "When thou sleepest, it shall keep thee." A keeper, or guard, implies danger in general, and in this instance in particular. There is a general danger in times of pestilence, and there is a special danger in some places and under some circumstances. There is a danger common to all vessels when sailing the ocean, but there are some parts which are especially dangerous. So it is with men in relation to sin. There is the general liability to fall into sin common to all men, but there are dangers which more especially beset youth and inexperience, and there is one sin above all others which is terrible in its effects and ruinous to the whole man. The text applies to a general keeping from the common danger and to a special keeping from this special danger (verse 24).