To understand this we must remember that the great prophecy in the book of Revelation is arranged in periods. Each seal, each trumpet, and each vial, represents a period. So there is one particular period of history foretold under the figure of the sixth vial, and all the events predicted under that vial we should expect to appear at about the same time in history. Whether we can trace any connexion or not, the events of each vial are linked together in respect of time; so that if there are two events under any one vial, when we see the one we ought to look out for the other, and when one takes place we have every reason to believe that the other is at hand. Now there are two events, apparently quite distinct in themselves, which are thus connected with each other under the sixth vial—the drying up of the Euphrates, and the appearance of certain most dangerous and seductive spirits, going forth to gather men together for the battle of Almighty God. If, therefore, it be a fact, as I firmly believe it to be a fact, that the Euphrates is now being dried up, then it follows as a sure and certain consequence that the unclean spirits are soon, if not already, going forth to do their deadly work. The two things go on according to the prophecy within the same prophetic period, and therefore if we see the one, as believers in the word of God, we ought to be on the lookout for the other. We are thus brought to the conclusion, that whenever the Euphrates shall be drying up, there will be a time of great spiritual seduction; or in other words that the exhaustion of the Turkish Empire will be accompanied, or quickly followed, by a remarkable development of mischievous spiritual power. This, then, must be our subject in this lecture, and we will study (if God permit) first the danger, and then the caution. May God grant that the result may be that we may be like those few men of Sardis who had not defiled their garments, and who will walk with the Lord Jesus in white, for they are worthy! I. The danger. This is described in Rev. xvi. 13, 14. ‘And I saw three unclean spirits like frogs come out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet. For they are the spirits of devils working miracles, which go forth unto the kings of the earth and of the whole world, to gather them to the battle of the great day of God Almighty.’ All students of prophecy are well aware how much has been written in exposition of these two verses, and what different explanations have been given of these three seductive spirits. I have not time this morning to discuss any of them, but there are three things perfectly clear, and it will be sufficient for us to study them. (1.) The subtlety of the danger.