Vs. 13-21. The sixth angel sounded the sixth trumpet, and when the trumpet sounded a voice commanded the sixth angel to loose the four angels that are bound in the great river Euphrates. The river Euphrates was the boundary between Israel and her ancient captors. It was across the Euphrates that Assyria came and carried Israel into captivity. And it was across the Euphrates that Babylon came and carried Judah into captivity. The great conquerors of Palestine and Egypt had come across the Euphrates in ancient times. It might well have an uncanny sound. This was at least a suggestion of conquest. The narrative goes on to say that the four Euphratan angels were loosed, and the number of the horsemen were two hundred thousand thousand. Thus without any explanation of these four angels a great army of horsemen are introduced and described showing that this symbol meant war. Now it is not certain whether this great army represented confederates of Rome that came from the east and assisted Rome in this Jewish war, or whether it has a general reference to the Roman armies only. That perhaps is not essential. But the vision portended war; and war in such gigantic proportions as to overwhelm completely the Jewish state. Two hundred thousand thousand horsemen would be of course impossible; but the number is impressive enough and was doubtless meant chiefly for impression. In this great army, the horses are described, but almost nothing said of the riders. The riders have breastplates of fire, jacinth, and brimstone; but the horses have heads of lions; fire, smoke, and brimstone issue from their mouths, and their tails were like serpents, with heads, that could bite. It has been supposed that this vision of cavalry would be very terrifying to the Jews, because they were not accustomed to use cavalry in warfare and had suffered in times past from this mode of warfare. The chapter closes by saying that the men who suffered from all these plagues did not repent of their sins, but continued to worship idols and even devils; the most offensive idolatry known to the prophets of God. The apostasy that refuses to repent, after all warnings, after preliminary judgments, has only one end, and that is destruction. And that end will surely come though God bear long with them. Old Antiochus Epiphanes, the worst persecutor the Jews ever had, whose memory was a nightmare, when afflicted with a dreadful disease, humbled himself and called on God, and declared if God would heal him he would himself become a Jew and proclaim God's mercy before the world. But these apostates of whom John writes did not repent though doom stared them in the face. This is a warning to all men to be sensitive in regard to their own sins; to heed God's warnings, and to repent and seek God's mercy. It is always a safe thing and a wise thing to repent of sin. The practical lessons of Revelation are many and forcible. With all its symbolism and mysteries, it deals with the vital things of human destiny.