He who knows both, knowledge and ignorance, together, overcoming death through ignorance, attains immortality through knowledge.

This is one of the most enigmatic and profound verses of the Kaṭha Upaniṣad. It seems paradoxical: how can avidyā (ignorance) be a means to overcome death (mṛtyuṃ tīrtvā)? The answer lies in understanding that avidyā here means knowledge of rites and virtuous actions that produce results in the world, not mere darkness.

Supreme vidyā is knowledge of the Ātman that liberates. But to reach it, one first needs avidyā — the fulfillment of duties, the practice of rites, the accumulation of merit (puṇya). This purifies the mind (citta-śuddhi) and makes it receptive to ultimate truth. It is like using a ladder that is then abandoned.

Knowledge of ubhayaṃ saha (both together) is crucial. It is not about choosing ignorance or knowledge, but understanding their dialectical relationship. The jñānī (knower) does not despise worldly actions; they use them consciously as preparation for the higher truth.

Amṛtam aśnute (attains immortality) is the final reward. Amṛta is not mere longevity but freedom from the cycle of birth and death. One who possesses vidyā feeds on this immortality, becomes it. Yoga is the path that integrates both knowledges — the relative and the absolute.