It is a very significant fact that the word which is translated in our Authorised Version 'prosperity' is often rendered 'security,' meaning thereby, not safety, but a belief that I am safe. A man who is prosperous, or at ease, is sure to drop into the notion that 'to-morrow will be as this day, and much more abundant,' unless he keeps up unslumbering watchfulness against the insidious illusion of permanence. If he yields to the temptation, in his foolish security, forgetting how fragile are its foundations, and what a host of enemies surround him threatening it, then there is nothing for it but that the merciful discipline, which this Psalmist goes on to tell us he had to pass through by reason of his fall, shall be brought to bear upon him. The writer gives us a page of his own autobiography. 'In my security I said, I shall never be moved.' 'Lord! by Thy favour Thou hast made my mountain to stand strong. Thou didst hide Thy face.' What about the security then? What about 'I shall never be moved' then? 'I was troubled. I cried to Thee, O Lord!'--and then it was all right, his prayer was heard, and he was in 'security'--that is, safety--far more really when he was 'troubled' and sore beset than when he had been, as he fancied, sure of not being moved. Long peace rusts the cannon, and is apt to make it unfit for war. Our lack of imagination, and our present sense of comfort and well-being, tend to make us fancy that we shall go on for ever in the quiet jog-trot of settled life without any very great calamities or changes. But there was once a village at the bottom of the crater of Vesuvius, and great trees, that had grown undisturbed there for a hundred years, and green pastures, and happy homes and flocks. And then, one day, a rumble and a rush, and what became of the village? It went up in smoke-clouds. The quiescence of the volcano is no sign of its extinction. And as surely as we live, so sure is it that there will come a 'to-morrow' to us all which shall _not_ be as this day. No man has any right to calculate upon anything beyond the present moment, and there is no basis whatever, either for the philosophical assertion that the order of nature is fixed, and that therefore there are no miracles, or for the practical translation of the assertion into our daily lives, that we may reasonably expect to go on as we are without changes or calamities. There is no reason capable of being put into logical shape for believing that, because the sun has risen ever since the beginning of things, it will rise to-morrow, for there will come a to-morrow when it will _not_ rise. In like manner, the longest possession of our mercies is no reason for forgetting the precarious tenure on which we hold them all.