Nakiketas said: "On this point even the gods have doubted indeed, and thou, Death, hast declared it to be not easy to understand, and another teacher like thee is not to be found: — surely no other boon is like unto this."

In plain words: Nachiketas refuses to back down. If even the gods were unsure, and if no teacher could explain it better than Death himself, then no other wish could be as valuable.