And what, let us ask, is sin? It is the acting of the will in opposition to God. It is doing our own pleasure--doing what we like ourselves. This is the root--this the source of sin. Let it take what shape, or clothe itself in what forms it may; be it gross or be it most refined in its actings, the great root-principle, the parent stem, is self-will, and this is sin. There is no necessity for entering into any detail; all we desire is that the reader should have a clear and thorough sense of what sin is, and not only so, but that he, by nature, is sinful. Where this great and solemn fact takes full possession of the soul, by the power of the Holy Ghost, there can be no settled rest until the soul is brought to lay hold on the truth set forth in 2 Corinthians v. 21. The question of sin had to be disposed of ere there could be so much as a single thought of reconciliation. God could never be reconciled to sin. But fallen man was a sinner by practice and sinful in nature. The very sources of his being were corrupt and defiled, and God was holy, just, and true. He is of purer eyes than to behold evil, and cannot look upon iniquity. Hence, then, between God and sinful humanity there could be no such thing as reconciliation. True it is--most blessedly true--that God is good, and merciful, and gracious. But He is also holy; and holiness and sin could never coalesce. What was to be done? Hear the answer: "God hath made Christ to be sin." But where? Reader, look well at this. Where was Christ made sin? Was it in His birth? or in Jordan's flood? or in the garden of Gethsemane? Nay; though, most assuredly, in that garden the shadows were lengthening, the darkness was thickening, the gloom was deepening. But where and when was the holy, spotless, precious Lamb of God made sin? _On the cross, and only there!_ This is a grand cardinal truth--a truth of vital importance--a truth which the enemy of God and His Word is seeking to darken and set aside in every possible way. The devil is seeking, in the most specious manner, to displace the cross. He cares not how he compasses this end. He will make use of anything and everything in order to detract from the glory of the Cross, that great central truth of Christianity round which every other truth circulates, and on which the whole fabric of divine revelation rests as upon an eternal foundation.