That (Ātman) difficult to see, hidden, entered into the secret place, dwelling in the cave (of the heart), abiding in the deep, the Ancient — knowing Him through the yoga of self-knowledge, the wise one abandons joy and sorrow.

This verse describes the elusive nature of the Ātman and the method for realizing it. Yama instructs Nachiketas on how the Self remains hidden even while being present at all times.

The Ātman is durdarśa (difficult to see) — not because it is far away, but because it is so close that it is overlooked. It is the eye that cannot see itself, the witness that cannot be witnessed. It is gūḍha (hidden, secret), not visible to ordinary senses or discursive mind.

Guhāhita — situated in the cave of the heart. The Upaniṣads frequently locate the Ātman in the hṛdaya-guhā, the cave of the heart. This is not the physical heart but the innermost center of consciousness. Gahvareṣṭha reinforces this interiority: it dwells in the deepest, most hidden place.

Purāṇa — the Ancient One. The Ātman has no temporal origin; it is prior to all creation, to all time. It is eternal not in the sense of infinite duration, but in transcending time itself.

The method revealed is adhyātma-yoga — the yoga of self-knowledge, the discipline of turning attention inward. The term anticipates the later use of yoga as systematic practice. The fruit of this knowledge is extraordinary: harṣa-śokau jahāti — the wise one abandons both joy and sorrow. This is not insensitivity but equanimity born from understanding that the real Self is beyond all pairs of opposites.