Bernhard Duhm in the context of "East Frisia"

The Book of Isaiah (Hebrew: ספר ישעיהו [ˈseː.fɛr jə.ʃaʕ.ˈjɔː.huː]) is the first of the Latter Prophets in the Hebrew Bible and the first of the major prophets in the Christian Old Testament. It is identified by a superscription as the words of the 8th-century BCE prophet Isaiah ben Amoz, but there is evidence that much of it was composed during the Babylonian captivity and later.

Johann Christoph Döderlein suggested in 1775 that the book contained the works of two prophets separated by more than a century, and Bernhard Duhm originated the view, held as a consensus through most of the 20th century, that the book comprises three separate collections of oracles: Proto-Isaiah (chapters 1–39), containing the words of the 8th-century BCE prophet Isaiah; Deutero-Isaiah, or "the Book of Consolation", (chapters 40–55), the work of an anonymous 6th-century BCE author writing during the Exile; and Trito-Isaiah (chapters 56–66), composed after the return from Exile. Isaiah 1–33 promises judgment and restoration for Judah, Jerusalem and the nations, and chapters 34–66 presume that judgment has been pronounced and restoration follows soon. While few scholars today attribute the entire book, or even most of it, to one person, the book's essential unity has become a focus in more recent research.

The servant songs (also called the servant poems or the Songs of the Suffering Servant) are four songs in the Book of Isaiah in the Hebrew Bible, which include Isaiah 42:1–4; Isaiah 49:1–6; Isaiah 50:4–11; and Isaiah 52:13–53:12. The songs are four poems written about a certain "servant of YHWH" (Hebrew: עבד יהוה, ‘eḇeḏ Yahweh). Yahweh calls the servant to lead the nations, but the servant is horribly abused by them. In the end, he is rewarded.

Some scholars regard Isaiah 61:1–3 as a fifth servant song, although the word "servant" (Hebrew: עבד, ‘eḇeḏ) is not mentioned in the passage. This fifth song is largely disregarded by modern scholars; without it, all four fall within Deutero-Isaiah, the middle part of the book, which some believe to be the work of an anonymous 6th-century BCE author writing during the Babylonian Exile. The five songs were first identified by Bernhard Duhm in his 1892 commentary on Isaiah.