V. Their Literary Characteristics. The prophecies in Isaiah 40-66 are psalms, sharing the characteristics of all lyric Hebrew poetry. Each is complete in itself and yet closely related to the others both in content and literary form. Their nobility of theme, their breadth of outlook, their wealth of rich and glowing figures, and their finished literary character give them an incontestable place among the greatest writings of the Old Testament. While there is a powerful argument running through them all, the logic is not cumulative but rather moves in a spiral, frequently returning to the same subject but having a gradual onward movement. It is the characteristic Oriental method of thinking, which is the opposite of that of the Western world. These poems are grouped into three cycles which apparently represent the prophet's thinking during succeeding periods. The first cycle is included in 40-48. Chapter 48 is a recapitulation of the thought of the preceding, and furnishes a natural conclusion to the first collection. The second group is in 49-55. The note of suffering is here more prominent, and the portrait of the ideal type of servant which Jehovah desires in order to realize his purpose in human history is developed in greater detail (cf. Section XCIX). The third group, in 56-66, is by many assigned to another prophet and to a much later period. While the general theme of the group is different and implies a somewhat changed historical background, the characteristic ideas and literary forms of 40-55 also recur here. From the study of Israel's past and future the prophet turns to the closer consideration of the problems in Palestine. The historical allusions are for the most part in accord with the conditions which Nehemiah found in Jerusalem in 445 B.C.