Who is Dr Scott Hahn that I should believe him?
Recommending a book instead of answering the question is a copout.
No. It's a recognition that what took a book to explain isn't going to be summarized terribly well here. If you insist, I will try (but it won't be anywhere near a complete argument)...
The Mass is the joining of Heaven and Earth. In the Mass, we participate in Christ's sacrifice on the Cross imaged in Revelation as the Lamb slain. There is a Heavenly reality to the Earthly liturgy. This reality is expressed in Revelation but understanding it requires an understanding of Tradition (big T)--especially the Liturgy of the Mass.