"Here I end this reel. Box--(pause)--three, spool--(pause)--five. (Pause. Perhaps my best years are gone. When there was a chance of happiness. But I wouldn't want them back. Not with the fire in me now. No, I wouldn't want them back."
What fire is Krapp speaking of above? Certainly not a physical one and doubtful of a mental fire. Krapp's fire lies in a bottle. His drink comforts him and befuddles his mind. He no longer trusts himself and therefor relies upon his tape. He has created a space in the world for him alone. Coming to terms with his past, he mocks his previously youthful voice and aspirations.