As I get ready to read through Isaiah in 6 months, this question needs to be asked. Or perhaps our would be: Who exactlyactly were the Isaiahs? Because this book is more complicated than we might think.
One of the problems we face in answering questions like this is that the Bible isn't like a modern book that has publisher's blurb. You don't get a handy little paragraph on the back cover saying something like "Isaiah lives in Jerusalem with his wife, two sons and a daughter. When he is not busy working in the Temple or writing his prophecies, he enjoys stamp collecting, drinking real ale and paragliding. But not necessarily at the same time."
No, we get none of that. All we can do is guess, from the clues in the words themselves. Because there is nothing else to go on.
So it seems clear that Isaiah was a Temple insider. A priest maybe, or a Levite. Or someone associated with the royal court, perhaps a historian or official recorder. Maybe he wrote some of the official history that we have in the books of Samuel and Kings. There are sections of his book that are identical to the historical passages, either included as direct quotes or reportage, or because Isaiah was actually drafting the official accounts.
And then something really weird happens. Between chapter 39 and 40, there is a time slip. Decades seem to have gone by, and suddenly we are talking about a very different situation. No longer are the Israelites at home in Jerusalem, suddenly the battles are over, their enemies have won and they are in exile.
If this is the same prophet speaking, then either he is very very old, or else he wrote a whole load of prophecies that had absolutely nothing to do with the times he lived in, and wouldn't have made much sense to him, but were just right for the future.
Or perhaps he was a time traveller.
Or - perhaps there were two of him. Or even three. Because there is another time slip later in the book, less well defined.
We'll think about these questions more when we get to the passages in question.
Just don't expect it to be a simple journey. There will be more questions than answers. But that's OK. Questions are good. They open us out to new possibilities. Answers are less good - they close down possibilities, and make us live in a world of black and white, right and wrong.