With this issue The Nation debuts a new feature: "Back Talk," Q&A's with literary, cultural and otherwise notable figures. "Back Talk" will appear on the last page of the magazine, where it will alternate from week to week with Frank W. Lewis's cryptic crossword. Puzzle fans need not feel crossed. The biweekly puzzle, as well as the solution to the previous puzzle, will be available online to all readers. This week "Back Talk " talks with Nicholson Baker.