in dating the Apocalypse if you know how to count kings.  I know how to count the seven dynasties of the Roman Empire.  Five have fallen, one is, the other has not yet come.  There is only one famous John who could have said that.  John Chrysostom was in Ephesus at the beginning of 401.  The third John of chapter one with John the Baptist and John the Apostle being the first two. Chapter 17 ties it altogether.  Babylon the Great, the two beasts, the seven heads, and the ten horns.