Daniel is to the Old Testament what Revelation is to the New Testament. There are so many prophecies, visions, dreams and if studied correctly, many fulfillments. The disciple, John, must have known his scriptures fairly well by this time in his life because the book of Daniel has so many recurring images in the book of Revelation that between Isaiah and Daniel, this author or Revelation shows his love of the scriptures. Specifically, when you are studying who are the four horsemen of the apocalypse, it may be easiest to study Daniel first to get an idea of what this particular Son of Thunder was talking about.
Granted, there are many other things that John is going through when he wrote Revelation and they all must be accounted for in order to try to make some semblance of the teaching in Revelation. A little background on John at this point shows that he was most certainly on the deserted island of Patmos at the time because he was sent there as a punishment. Luckily, his punishment did not mean death like it surely meant for the other disciples at an earlier time in their ministry.
Actually, the reason that John, the brother of James, was sent to Patmost was most surely so that he would die eventually. This was not an island where he was sent to relax and get rested up for his next ministry time period in life. People were sent to this island as a punishment with no food, extreme weather conditions, and most never made it out alive. John on the other hand, witnessed an amazing vision in which he then wrote the book of Revelation from.
One of the many visions that John had was obviously describing who are the four horsemen of the apocalypse. One theory is that John was by this time dehydrated, lacked sleep and getting delusions of grandeur. This may very well be part of the story, but certainly not the entirety. To be able to relate so many parts of the Old Testament, specifically Daniel and Isaiah means that our dear disciple John was much more coherent than many historians would like to give him credit for. He knew very well what he was writing about and may have done it in code to avoid further punishment before believers saw what he saw in his visions.
