Revelation 1:11: Saying, I am Alpha and Omega, the first and the last: and, What thou seest, write in a book, and send it unto the seven churches which are in Asia; unto Ephesus, and unto Smyrna, and unto Pergamos, and unto Thyatira, and unto Sardis, and unto Philadelphia, and unto Laodicea.
“It has pleased the Lord to mention these seven, to send the book of Revelation to them, not to show the church in seven different periods, as being dealt with in the sequel, but to make them serve for the transmission of this book to other churches, and to strengthen them into seven witnesses. It also serves to show that the Lord Jesus has His eye on His church after His ascension and is present among her, and as an example for all churches, to follow what is praised in these churches, and to refrain from that which is reproved in them, and to serve as an example of the acts of the Lord Jesus with the churches, which re thus set as these. This is what was heard.”
Revelation 1:19: Write the things which thou hast seen, and the things which are, and the things which shall be hereafter;
“Some think that the seven letters are prophetic, and signify seven periods. They, seeing that this verse destroys their opinion, try to bring these three so distinct matters to two, namely, to the signs and the explanation of the signs, whether of all that are included in Revelation, or of the first vision in this chapter. But the text is clear and states threefold matters of threefold times. Revelation clearly contains those threefold matters of threefold times One had happened; the other, the state of the church, was present; the third would happen. The fourth chapter starts with the words, Come up higher, and I will shew thee things which must be hereafter.”
“We say to the question presented above that the seven letters, seals, trumpets, and vials do not signify seven periods or determined time orders; that the letters are not even prophetic; that the other symbols do not represent times, but matters, which the church and the enemy of the church will subsequently meet.”
~Wilhelmus a Brakel, Not to be Ignored: Rev. Wilhelmus a Brakel’s Commentary on Revelation (McCarter Providential Enterprises LLC: 2016), pages 9, 15, and 18