Why is The Voice Behind John?

I was in the Spirit on the Lord's day, and I heard behind me a loud voice like a trumpet saying, “Write what you see in a book and send it to the seven churches, to Ephesus and to Smyrna and to Pergamum and to Thyatira and to Sardis and to Philadelphia and to Laodicea.” -Revelation 1:10-11

Why is the voice behind John? The book of Revelation is about revealing, unveiling what we do not see but is there. This dramatic action embodies that principle. There is something there, next to John, that John does not see, just like the book of Revelation. John must turn, reorient his life to attend to this unveiling. It is only when he turns that the message is unveiled.