Death said: "The Self-existent pierced the openings (of the senses) so that they turn forward; therefore man looks forward, not backward into himself. Some wise man, however, with his eyes closed and wishing for immortality, saw the Self behind.

In plain words: Death, still teaching the boy Nachiketas, says the Creator made our senses point outward, so people look out at the world instead of inward. But a wise person who wanted to live forever closed his eyes, looked within, and saw the true Self.