The Catholic Study Bible (1990) affirms Proto-Isaiah (1-39) in addition to Deutero-Isaiah (40-55) and Trito-Isaiah (56-66). In this way, the predictive prophecy about King Cyrus is denied. There are good reasons to believe the book was composed in the 8th century B.C. by St. Isaiah. The Dead Sea Scrolls, Septuagint (LXX), Qumran, and other ancient texts don’t indicate multiple authorship. The LXX heading for the entire book is “The vision concerning Judah and Jerusalem that Isaiah son of Amoz saw during the reigns of Uzziah, Jotham, Ahaz and Hezekiah, kings of Judah.” Later prophets (Nahum 1:15 on Is 52:7; Zeph 2:15 on Is 47:8,10) refer to Deutero-Isaiah as the work of one author, Isaiah. Ecclesiasticus (Sirach) 48:22-25 refers to Trito-Isaiah as the work of the “original” Isaiah. Jesus Christ and other New Testament figures referred to the entire book as the work of the one Isaiah. Josephus in Antiquities XI, 3-6 –i. 1-2 states that the book has one author, the prophet Isaiah. Deutero-Isaiah and Trito-Isaiah contain Messianic prophecies and should be attributed to Isaiah. The whole book has great unity in perspective, language, and style, mentioning the “Holy One of Israel.” Both the first part and second part of Isaiah tell us about a Messiah who is a Servant and a King. I realize that the title itself does not indicate authorship, but there are excellent reasons to believe that Isaiah is the author of the book.