The more one studies the problem of the authorship of these chapters, the more unlikely does it seem that their author penned them 150 years before the time with which they are vitally connected. It is obviously impossible to treat that problem in a detailed way here, but one may sum up the arguments by saying that in theological ideas, in style, and use of words they show such differences from the assured productions of Isaiah's pen as to point to a different authorship. And the great argument, the argument which carries the most weight to the author of this article, is that these late chapters are written from the standpoint of the exile. The exile is assumed in what is said. These chapters do not prophesy the exile, do not say it is to come; they all the time speak as though it had come. The message is not that an exile is to be, but beginning with the fact that the exile already is, it foretells deliverance. Now of course it is conceivable that God might inspire a man to put himself forward
150 years, and with a message to people who were to live then, assuming their circumstances as a background of what he said, but it is improbable to the last degree. To put it in plain, almost gruff, English, it is not the way God did things. The prophet's message was always primarily a message to his own age. Then there is no claim in the chapters themselves that Isaiah was their author. And having once been placed so that it was supposed they were by Isaiah-placed so through causes we do not know-the fact that in speaking of passages from these chapters New Testament authors referred to them by a name the people would recognize, is not a valid argument that they meant to teach anything as to their authorship. The problem had not arisen in New Testament times.
Isaiah 40-66, as Professor Davidson has suggested, has a parallel in the Book of Job, each the production of a great mind, each from an author we do not know.