The book of Isaiah is the Romans of the Old Testament and what some have called the fifth Gospel. It is the third-longest book in the Bible. Isaiah is the first of the Major Prophets in the sequence of the canon of Scripture. More is revealed about Christ in Isaiah than any other Old Testament prophetic book.
Isaiah is the Bible in miniature. There are 66 books in the Bible and 66 chapters of Isaiah. There are 39 books of the Old Testament, and 39 chapters in the first section of Isaiah. There are 27 books in the New Testament and 27 chapters in the second half of Isaiah. Similarly, Isaiah 40 begins with a voice crying in the wilderness and the New Testament begins with John the Baptist, the voice of one crying in the wilderness. Further, Isaiah 1 is equivalent to the first book of the Bible, Genesis. Isaiah 40 is equivalent to Matthew. Isaiah 66 is equivalent to Revelation; and Isaiah and Revelation contain the seven verses where God reveals Himself as the first and the last.