Just to satisfy my curiosity, can anyone tell me whether the quotation from the work appears in the current edition of ODQ. In my edition, the sixth, there is only one quote from the work and it's completely irrelevant. I had to google for other quotes to find the relevant one. That's not very satisfactory since Listener puzzles are not supposed to be dependent on the internet. I suppose one could trawl through the whole work, but that's a tall order.
I thought the clues pretty poor on the whole; some of the surfaces barely make sense. I expect more from a Listener puzzle.