The immutable consciousness, assuming the form of the mind, experiences its own cognition.

This sutra describes the mechanism of knowledge. Citi (pure consciousness) is apratisaṅkrama, it does not move or change. However, it “assumes the form” (ākāra āpatti) of buddhi, intelligence.

It is not that puruṣa really transforms. Rather, the mind, refined by practice, becomes so transparent that it perfectly reflects the light of consciousness. In that reflection, consciousness appears to know.

Svabuddhi saṃvedanam is “experiencing its own cognition.” Consciousness, reflected in buddhi, knows itself through that reflection.

It is like the sun reflected in still water: the sun doesn’t descend into the water, but its image appears there. Similarly, puruṣa doesn’t enter the mind, but its reflection produces the experience of knowledge.

When buddhi is completely purified and still, the reflection is so clear that the distinction between puruṣa and its reflection is recognized. This is liberation.