Many of the later additions possess a value and authority entirely independent of that possessed by the prophet with whose writings they have been joined by their original authors or later editors. Thus the sublime chapters appended to the original sermons of Isaiah contain some of the noblest teachings in the Old Testament. The different themes and literary style; the frequent references to the Babylonians, not as distant allies, as in the days of Isaiah the son of Amoz, but as the hated oppressors of the Jews; the evidence that the prophet's readers are not exiles far from Judah; the many allusions to the conquests of Cyrus,--all these leave little doubt that chapters xl.-lv. were written in the latter part of the Babylonian or the first of the Persian period. Interpreted in the light of this background, their thought and teachings become clear and luminous. Similarly, the varied evidence within the chapters themselves seems to indicate that Isaiah lvi.-lxvi. contain sermons directed to the struggling Jewish community in Palestine during the days following the rebuilding of the temple in 520 B.C. [Sidenote: _The order and date of the prophetic books_] The prophetic sermons, epistles, and apocalypses fall naturally into five great groups. The books prophets of the Assyrian period were Amos and Hosea, who between 750 and 734 B.C. preached to Northern Israel; also Isaiah and Micah, whose work lies between 740 and 680 B.C. Nahum's little prophecy, although much later, echoes the death-knell of the great Assyrian kingdom, which for two or three centuries dominated southwestern Asia. The prophets of Judah's decline were Zephaniah (about 628 B.C.), Jeremiah (628-690), and Habakkuk (609-605). To the same period belong Ezekiel's earlier sermons, delivered between 592 and 586, just before the final destruction of Jerusalem. The prophets of the Babylonian exile were Obadiah, whose original oracle belongs to its opening years; Ezekiel (xxv.-xlviii.), who continued to preach until 572 B.C., and the great prophet whose deathless messages ring through Isaiah xl.-lv. The prophets of the Persian period were Haggai and Zechariah, whose inspiring sermons kept alive the flagging zeal of those who rebuilt the second temple; the authors of Isaiah lvi.-lxvi.; the author of the little book of Malachi; and Joel. To this list we may perhaps add the prophet who has given us that noble protest, found in the much misunderstood book of Jonah, against the narrow and intolerant attitude of later Judaism toward foreigners. [Sidenote: _Growth of anonymous and apocalyptic literature_]