From time to time, when someone asks why, given my age, I haven’t retired, I explain that I really enjoy editing what others write. The truth, though, is that the pleasure waxes and wanes. If a story is good enough to require very little editing, my work is easy but not much fun. If a narrative is jammed full of extraneous words and ideas — or if the most compelling information is left for the bitter end — editing can be tough.