The deepest ground of that necessity lies in the fact of sin. Brother, we can only verify our Lord's assertion by honestly searching the depths of our own hearts, and looking at ourselves in the light of God. Think what is meant when we say, 'He is Light, and in Him is no darkness at all.' Think of that absolute purity, that, to us, awful aversion from all that is evil, from all that is sinful. Think of what sort of men they must be who can see the Lord. And then look at yourself. Are we fit to pass that threshold? Are we fit to gaze into that Face? Is it possible that we should have fellowship with Him? Oh, brethren, if we rightly meditate upon two facts, the holiness of God and our own characters, I think we shall feel that Jesus Christ has truly stated the case when He says, 'Ye must be born again.' Unless you and I can get ourselves radically changed, there is no Heaven for us; there is no fellowship with God for us. We must stand before Him, and feel that a great gulf is fixed between us and Him. And so when a man comes with his poor little 'Thou art a Teacher,' no words are wanted in order to set in glaring light the utter inadequacy of such a conception as that. What the world wants is not a Teacher, it is a Life-giver. What men want is not to be told the truth; they know it already. What they want is not to be told their duty; they know that too. What they want is some power that shall turn them clean round. And what each of us wants before we can see the Lord is that, if it may be, something shall lay hold of us, and utterly change our natures, and express from our hearts the black drop that lies there tainting everything. Now, this necessity is met in Jesus Christ. For there were two 'musts' in His talk with Nicodemus, and both of them bore directly on the one purpose of deepening Nicodemus's inadequate conception of what He was and what He did. He said, 'Ye must be born again,' in order that his hearer, and we, might lay to heart this, that we need something more than a Teacher, even a Life-giver; and He said, 'The Son of Man must be lifted up,' in order that we might all know that in Him the necessity is met, and that the Son of Man, who came down from Heaven, and is in Heaven, even whilst He is on earth, is the sole ladder by which men can ascend into Heaven and gaze upon God.