The key to unlock the meaning and scope of the book is found in 1:10. "The Lord's day" = THE DAY OF THE LORD (Jehovah). (See Isaiah 2:12) John was not in "a state of spiritual exaltation" on any particular Sunday at Patmos, as the result of which "he saw visions and dreamed dreams". But as we are told, "I came to be (or found myself) by the Spirit in the day of the Lord" (compare Ezekiel 1:1; 8:3, etc.). He is then shown, and both sees and hears (22:8), the things he records.
"The day of the Lord" being yet future, it follows that the whole book must concern the things belonging to "that day", and consequently is wholly prophecy. Though partial adumbrations of judgment may be traced in connection with affairs of past history, yet the significant, solemn warning here (1:10) that the "judgments" in Revelation relate to the day of the Lord, "the day of vengeance" (compare Isaiah 61:2; 63:4, etc.), makes it clear that the book concerns the future, and the day of the unveiling (the Apocalypse) of the great "King of kings and Lord of lords"