I woke up very early today and couldn't fall back asleep. So I started to read the book of Isaiah. 

It never really occurred to me before how remarkably similar the first eleven chapters are to the Revelation to John. Much of the content in these beginning chapters project far into the future. It spotlights the condition of the nation of Israel. It's very detailed in its description of Israel's spiritual condition, its disciplinary correction, and its path to restoration through the "Branch of David". 

Whereas the Revelation to John has a much broader scope - Israel, the Church, the world, and even the unseen realm are in view. Both books end up in the same place. But if you find the Revelation to John difficult, the beginning chapters of Isaiah are a good introduction.