“At thy right hand there are pleasures for evermore” (Ps. 16:11)
“After this I looked, and, behold, a door was opened in heaven: and the first voice which I heard was as it were of a trumpet talking with me; which said, Come up hither, and I will shew thee things which must be hereafter” (Rev. 4:1).
The first three chapters of Revelation should be considered as preamble. John is setting the stage, describing the reasons for the revelation that is about to be made manifest. Remember that the entire book is going to be read to the Philadelphians, to the Laodiceans, to the Thyatirans, and so on. This revelation is going to land in their respective churches very differently. Those in Philadelphia are already overcomers, and so they are ready for what this book contains. Those in Laodicea are not ready, at least not apart from repentance. The truth is always constant, but it strikes different levels of inconstancy differently.
John looked and a door in the heavens opened up. He heard a voice that was described as “the first voice,” and the voice sounded like a trumpet talking. John is invited up into the heavens so that he might be shown the things which were to come “hereafter.” Given what has been said in the preamble, and from details of the revelation itself, we know that these events will be shortly hereafter. John was not being shown the distant future. When Daniel was shown the distant future, he was told to seal the words of the prophecy because the fulfilled events were still 4 centuries in the future. John is told not to seal what he sees, and it would be odd if the events were 20 centuries out and counting.
The other thing to note here is that we see the development of a “two-layer” structure for the remainder of the book. Those two layers are the history of Heaven and the history of earth. God is worshiped in Heaven, and dramatic things are accomplished on earth. God is glorified in Heaven, and God is glorified on earth. And this is how we pray—may Your will be done on earth as it is in Heaven.