When the kumbhaka is perfected, the prāṇa diminished and unsupported, then rajas is burned;That is why the mind achieves purity.

This verse describes the yogic mechanism of mental purification.Kumbhakaḥ siddhaḥ — when breath retention is perfected, not as an effort but as a stable achievement.The prāṇa becomes kṣīṇa (diminished, subtle) and nirāśraya (without external support, self-sustained).

The result is that rajas — the quality of activity, agitation, passion — is dagdha (burned, consumed).Of the three guṇas (sattva, rajas, tamas), rajas is particularly responsible for mental restlessness, incessant desires, inability to be at peace.

When rajas is consumed, the mind attains nirmalatā — purity, clarity, transparency.This is not a moralistic purity but the quality of a clean mirror that reflects without distortion.The Bihar School emphasizes the causal connection: it is not that mental purity produces kumbhaka but that kumbhaka produces mental purity.Haṭha yoga works from the body to the mind.