One who does not know this would be an enemy. The letter A is all that is manifest, and also is the origin. The explanation of A is its condition of Vaiśvānara. One who knows thus becomes all that is manifest.

This mantra expands mantra 8 with two crucial additions.

Amitraḥ syād yo na veda: one who does not know (na veda) this would be an enemy (amitraḥ). “Enemy” here does not mean external antagonist, but one who is in conflict with oneself. One who ignores the nature of A ignores waking as a manifestation of Brahman — and therefore remains trapped in it as ultimate reality.

Vidvān bhavati sarvaṃ vyaktiṃ: one who knows (vidvān) becomes (bhavati) all manifestation (sarvaṃ vyaktiṃ). It is not about intellectual knowledge but direct identity. Knowing the nature of A is not knowing something about waking — it is being waking consciously.

This is the first of the three promises of realization (mantras 11-12-12b correspond to A, U, M). Each letter, correctly understood, not only describes a state of consciousness but is the key to transforming one’s relationship with that state.

The structure is deliberately symmetrical: the same descriptive phrase from mantra 8 repeats, but now framed by the consequence of knowing or not knowing.