In the very first verse of Revelation, John provides us with an important interpretive key: "The Revelation of Jesus Christ, which God gave Him to show His servants what must shortly take place; and He sent and signified it by His angel to His servant John" (Rev. 1:1). The use of the term signify tells us that the prophecy is not simply to be taken as "history written in advance." Instead, it is a book of signs: symbolic representations of the coming events. The symbols are not to be understood in a literal manner. We can see this by John's use of the term in his Gospel (see John 12:33; 18:32; 21:19). In each case, it is used of Christ signifying a future event by a, more or less, symbolic indication, rather than by a clear and literal description. And this is generally the form of the prophecies in the Revelation. This does not mean the symbols are unintelligible; the interpretation is not up for grabs. On the other hand, I am not saying that the symbols are in some kind of code, so that all we need is a dictionary or grammar of symbolism to "translate" the symbols into English. Prophecy is poetry, not naive or static allegory. The only way to understand its symbolism is to become familiar with the Bible. The Biblical standard for interpretation is the Bible itself.