When this psalm was written, or what particular events it speaks of, I cannot tell, for I do not think we have any means of finding out. It may have been written in the time of David, or of Solomon, or of Hezekiah. It may possibly have been written much later. It seems to mo probably to refer--but I speak with extreme diffidence--to that Assyrian invasion, and that preservation of Jerusalem, of which we heard in the magnificent first lesson for this morning and this afternoon; when, at the same time that the Assyrians were crushing, one by one, every nation in the East, there was, as the elder Isaiah and Micah tell us plainly, a great volcanic outbreak in the Holy Land. But all this matters very little to us; because events analogous to those of which it speaks have happened not once only, but many times, and will happen often again. And this psalm lays down a rule for judging of such startling and terrible events whenever they happen, and for saying of them, "God is our refuge and strength, a very present help in trouble." It seems from the beginning of the psalm that there had been earthquakes or hurricanes in Judea--more probably earthquakes, which were and are now frequent there. It seems as if the land had been shaken, and cliffs thrown into the sea, which had rolled back in a mighty wave, such as only too often accompanies an earthquake. But the Psalmist knew that that was God's doing; and therefore he would not fear, though the earth was moved, and though the hills were earned into the very midst of the sea. It seems, moreover, that Jerusalem itself had, as in Hezekiah's time, not been shaken, or at least seriously injured, by the earthquake. But why? "God is in the midst of her, therefore shall she not be removed." It seems, also, as if the earthquake or hurricane had been actually a benefit to Jerusalem-- which was often then, and has been often since, in want of water--that either fresh springs had broken out, or abundant rain had fallen, as occurs at times in such convulsions of nature. But that, too, was God's doing on behalf of His chosen city. "The rivers of the flood" had made "glad the city of God, the holy place of the tabernacle of the most highest."