The vision that John saw in Revelation 4-5 concludes the opening section and prepares for the rest of the book.  After reading about the difficulties in the seven churches, we get a glimpse of the heavenly control room and witness a two-part worship service focused on a central throne.  This second vision reminds us of what is really happening in the universe and helps us to keep going amidst the difficulties of our world and our lives.  We must worship God, because he is worthy, and also so that we can persevere to the end.