Of the size of a thumb, the Puruṣa, the inner Self, is always seated in the heart of beings. One should draw Him out from one’s own body with firmness, like the stalk from the muñja grass. Know Him as pure and immortal — know Him as pure and immortal.

This verse concludes the Kaṭha Upaniṣad with an extraordinary image that combines the immensity of the Puruṣa with a concrete localization and a practical instruction.

Aṅguṣṭha-mātra — of the size of a thumb. This measure appears in various Upaniṣads and should not be understood literally. The thumb represents concentrated essence: the infinite Self becomes accessible in the space of the heart. It is a concession to the mind that needs a point of focus.

Antara-ātmā — the inner Self, the inner soul. Hṛdaye saṃniviṣṭaḥ — firmly established in the heart. The Puruṣa does not visit occasionally; it is always (sadā) present in all beings (janānām).

Svāt śarīrāt pravṛhet — one should extract it from one’s own body. The image is striking: like one who carefully separates the inner stalk of the muñja grass from its outer covering. The process requires dhairya — firmness, patience, courage.

This “extraction” is not physical but cognitive: it is the discernment (viveka) that separates the Self from its sheaths — body, prāṇa, mind, intellect. The yogi learns to recognize: “I am not the body, I am not the mind — I am the witness of all this.”

Taṃ vidyāt śukram amṛtam — know Him as pure and immortal. The repetition at the end of the verse (iti) marks the conclusion of the Upaniṣad. Direct knowledge (vidyā) of the Puruṣa as luminous (śukra) and immortal (amṛta) is the goal of the entire dialogue between Yama and Nachiketas.

The young man who arrived at the realm of Death seeking to know what lies beyond receives the definitive answer: the Self that is already in your heart is immortal. There is nowhere to go; there is only knowing what you already are.