Consist of two divisions, the first extending from chap. i. to chap. xxxix., and the second from chap. xl. to the end; these two divisions were for long believed to be throughout the work of Isaiah the son of Amoz, but modern criticism assigns them in the main to different authors, the one living 150 years after the other; and the reasons for this conclusion are that the author of the latter belonged to a different period of Jewish history from that of the former, is not of the same temper, and has much deeper spiritual insight, while his hopes and expectations are built on a more spiritual view of the method of salvation, the Messiah of the former, for instance, being a conquering king, and that of the latter a suffering Redeemer, who to save the nation has to bear the burden of its sins, and the brunt of them, and so bearing, bear them away.