The Unity of the Book. 

        The structure of Isaiah is unique. The first thirty-five chapters are attributed to Isaiah the son of Amoz, and are dated in the period Uzziah to Hezekiah. This first section, commonly called Proto-Isaiah by scholars — we use these names for convenience, not to prejudge the question of authorship — is closed by four historical chapters from the time of Hezekiah, which can be, but quite probably are not, from the pen of Isaiah. There follows an anonymous col­lection of prophecies (chs. 40-55 — Deutero-Isaiah) in which it seems “the Babylonian Exile is not predicted; it is described as an existing fact” (Kirkpatrick, p. 359.). The book ends with a less homo­geneous section (chs. 56-66 — Trito-Isaiah) in which the general picture seems to be the position after the return from exile.

        The most obvious interpretation of these phenomena is that we have the work of one, or possibly two, anonymous prophets appended to the prophecies of Isaiah. Nor does the New Testament necessarily dispel such a view, for the at­tribution of passages from “Deutero-” and “Trito-Isaiah” to Isaiah might mean no more than that they were taken from the book which circulated under that name. The moment, how­ever, that the phenomena of the book are examined more closely, the more difficult this apparently simple theory is seen to be.

        We cannot here enter into questions of style, language and theology. It will suffice to say that the differences in these spheres between “Proto-” and “Deutero-Isaiah” are sufficient to suggest possible difference in authorship; the similarities demand some connexion between them.

        When we consider the increasing complexities demanded by the usual modern view, and the many improbabilities it in­volves, it is surely easier to accept the traditional view of the isaianic authorship of the whole prophecy. It must, however, be stressed that here, as in many other Old Testament problems, we are dealing with probabilities, not provable certainties (For the unity of Isaiah see Young pp. 202-211, ISBE, article Isaiah, against HDB, article Isaiah, Driver LOT pp. 236-246).