What, then, is the force of that name? We do not need, I suppose, to do more than simply remind you that there are two great thoughts communicated by that self-revelation of God which lies in it. _Jehovah_, in its literal grammatical signification, puts emphasis upon the absolute, underived, and therefore unlimited, unconditioned, unchangeable, eternal being of God. 'I AM THAT I AM.' Men and creatures are what they are made, are what they become, and some time or other cease to be what they were. But God is what He is, and is because He is. He is the Source, the Motive, the Law, the Sustenance of His own Being; and changeless and eternal He is for ever. In that name is the Rock of Ages. That mighty name, by its place in the history of Revelation, conveys to us still further thoughts, for it is the name of the God who entered into covenant with His ancient people, and remains bound by His covenant to bless us. That Is to say, He hath not left us in darkness as to the methods and purpose of His dealings with us, or as to the attitude of His heart towards us. He has bound Himself by solemn words, and by deeds as revealing as words. So we can reckon on God. To use a vulgarism which is stripped of its vulgarity if employed reverently, as I would do it--we know where to have Him. He has given us the elements to calculate His orbit; and we are sure that the calculation will come right. So, because the name flashes upon men the thought of an absolute Being, eternal, and all-sufficient, and self-modified, and changeless, and because it reveals to us the very inmost heart of the mystery, and makes it possible for us to forecast the movements of this great Sun of our heavens, therefore in the name '_Jab Jehovah_ is the Bock of Ages.' The metaphor needs no expansion. We understand that it conveys the idea of unchangeable defence. As the cliffs tower above the river that swirls at their base, and takes centuries to eat the faintest line upon their shining surface, so the changeless God rises above the stream of time, of which the brief breakers are human lives, 'sparkling, bursting, borne away.' They who fasten themselves to that Rock are safe in its unchangeable strength, God the Unchangeable is the amulet against any change, that is not growth, in the lives of those who trust Him. Some of us may recall some great precipice rising above the foliage, which stands to-day as it did when we were boys, unwasted in its silent strength, while generations of leaves have opened and withered at its base, and we have passed from childhood to age. Thus, unaffected by the transiency that changes all beneath, God rises, the Bock of Ages in whom we may trust. 'The conies are a feeble folk, but they make their houses in the rocks.' So our weakness may house itself there and be at rest. IV. Lastly, note the summons to trust.