Revelation employs at least three genres. The very first word of the book, in Greek, is apocalypse or "apokalupsis," so, this book, John is identifying it as a "revelation" or perhaps an "unveiling." So it's, number one, it's an apocalypse which is, it's as though the veil is being pulled back, and people are being allowed to see things as they really are. Number two, it's a prophecy. Revelation 1:3: "Blessed is the one who reads aloud the words of this prophecy." So I think we can say that Revelation is an apocalyptic prophecy. And some have distinguished between an apocalypse, being concerned with the events of the very end of history, the consummation of all things, and perhaps, heavenly realities, and then a prophecy, dealing with the actual outworking of history. And then thirdly, Revelation employs features of an epistle. So around verse 4, John begins to say, "John, to the seven churches," and then he addresses those seven churches. There's a blessing much like the format of Paul's letters. So if you compare Revelation 1:4-8 or so, the opening there is very similar to the opening of some of Paul's letters. And then it concludes, the whole book concludes with a grace that is very similar to the way that Paul concludes his letters. So I think we can say that Revelation is an apocalyptic prophecy in the form of a circular letter. And there was probably a letter carrier who would have delivered this writing to these churches, and then read it aloud in Christian worship.