So, as I was finishing up the LeGuin interview book* tonight I came across an unexpected passage:
Writers are often asked, "Why do you write?"
which is, you know, an impossible question.
But a lot of them give that very answer.
I wrote it because no one else would,
and I wanted to read it. Tolkien, as a
matter of fact, said that -- he said, "I knew
nobody else could write it, because
nobody else knew about Middle Earth."
--The Gift of Place (1977), page 23*
I've read a lot of Tolkien interviews --all that I cd find-- and this quote's not familiar to me.
I don't think Le Guin just made it up, but if not where did it come from?
What I suspect is that the story about Tolkien and Lewis's bargain to write stories for each other (Tolkien's the time-travel story THE LOST ROAD and Lewis's the space travel book OUT OF THE SILENT PLANET). If that's so then somehow the original story (via LETTERS OF JRRT or Carpenter's biography) must have wandered from its initial context and gotten garbled in the process.
If anyone knows of a more proximate source I'd be glad to hear of it.
*THE LAST INTERVIEW, ed. David Streitfeld (2019). I read the essays in reverse order, which made for an interesting experience.