The book of Revelation is hard to understand. This is why God in His wisdom uses signs to make it known to us. Revelation 1:1 says that God gave the revelation of Jesus Christ to Him to show to His slaves; "and He made it known by signs." Signs are pictures. In teaching little children we make things known to them by pictures. Sometimes when I speak, I make things known by diagrams. John received a revelation concerning things so divine, so mysterious, so profound, that no human words could explain it adequately. Thus the revelation was made known by signs.
Not only the book of Revelation but John's Gospel also is a book of signs. In our Life-study of that Gospel I pointed out that the word miracle is not used. (Where the King James Version has "miracle," the proper rendering is "sign.") The Lord's changing water into wine was a miracle, but John calls it a sign (2:11), indicating that it has a meaning. The Lord's changing water into wine signifies His changing death into life. Lazarus's resurrection was a miracle, but John calls it a sign (11:47).
John 1:14 speaks of the Word becoming flesh and tabernacling among us. "Tabernacled" is a verb. This sign gives us the key to understand how the Lord Jesus lived on this earth. He lived here as God's tabernacle. To fully understand the tabernacle, we must go back to Exodus, where several chapters describe the tabernacle. God's tabernacle among His people was not only where He dwelt but also where His serving ones entered to dwell with Him. This is Jesus! While Jesus was on this earth, He was tabernacling. God abode in Him and all God's serving ones, Jesus' lovers, could enter into Him to stay with God. This one word as a sign describes what no plain word could express.
Also in John the Lord Jesus says, "I am the door" (10:7). Do you believe that the Lord is a door with a lintel and a post? A door is a sign, meaning that He is the very opening for people to enter in and for them to come out.
We must emphasize the very first verse of Revelation, which says that the divine revelation is given to Jesus Christ and that He makes it known by signs. This is the key to open up the entire book. Without this key, the book of Revelation is closed to us. To understand the real meaning of this book, we must understand these signs.