Psalms 90:2

2Before the mountains were brought forth. Moses designs to set forth some high and hidden mystery, and yet he seems to speak feebly, and, as it were, in a puerile manner. For who does not know that God existed before the world? This we grant is a truth which all men admit; but we will scarcely find one in a hundred who is thoroughly persuaded that God remains unchangeably the same. God is here contrasted with created beings, who, as all know, are subject to continual changes, so that there is nothing stable under heaven. As, in a particular manner, nothing is fuller of vicissitude than human life, that men may not judge of the nature of God by their own fluctuating condition, he is here placed in a state of settled and undisturbed tranquillity. Thus the everlastingness of which Moses speaks is to be referred not only to the essence of God, but also to his providence, by which he governs the world. Although he subjects the world to many alterations, he remains unmoved; and that not only in regard to himself, but also in regard to the faithful, who find from experience, that instead of being wavering, he is steadfast in his power, truth, righteousness, and goodness, even as he has been from the beginning. This eternal and unchangeable steadfastness of God could not be perceived prior to the creation of the world, since there were as yet no eyes to be witnesses of it. But it may be gathered a posteriori; for while all things are subject to revolution and incessant vicissitude, his nature continues always the same. There may be also here a contrast between him and all the false gods of the heathen, who have, by little and little, crept into the world in such vast numbers, through the error and folly of men. But I have already shown the object which Moses has in view, which is, that we mistake if we measure God by our own understanding; and that we must mount above the earth, yea, even above heaven itself, whenever we think upon him.