Deutero-Isaiah and Trito-Isaiah

I am writing this to try to make sure I understand some of the differences between Second and Third Isaiah, as presented by Coogan and our HarperCollins NRSV notes.

First of all, we separate Second Isaiah from First Isaiah because it addresses the problem of the Babylonians, rather than the Assyrians as in First Isaiah. Second Isaiah also does not name its author or specify any details about his life, whereas in First Isaiah the prophet is a named character in the narrative. The character of Cyrus the Persian is another differentiating factor. Cyrus is not mentioned at all in First Isaiah, but is given great importance in Second Isaiah. Despite his obvious pagan status, he is exalted as the "shepherd" and the "anointed one," and Yahweh has chosen him to rise up against the Babylonians. He has also been chosen to rebuild the Temple, which is another point of departure from First Isaiah, wherein the Temple, as well as Jerusalem as a whole, had not yet been destroyed. Second Isaiah is concerned with the possibility of restoration rather than the threat of destruction.

In Third Isaiah, the context clearly shifts once again. Second Isaiah is mainly concerned with the return from exile, but in Third Isaiah, the Temple seems actually to have been rebuilt, or at least the people are in the process of rebuilding. Also, while Second Isaiah is addressed to the people in exile in Babylon, Third Isaiah is addressed to the people of Judah. Therefore, Third Isaiah, although there are difficulties with its dating, seems to have its source in the early postexilic period, likely in the fifth or sixth century BCE.