Yoga Sutra 1.47 skill in nir-vicara, a clearness in the self
From skill in nir-vicāra, a clearness in the self
When the mind-sattva whose nature is light, is freed from rajas and tamas, and has a clear steady flow, without any veiling contamination of impurity, that is the skill in nir-vicāra. When this skill in nir-vicāra appears, there is an inner clearness in the self of the yogin, which is a progressively (anurodhi) clearer and brighter light of knowledge of the object as it really is.
The veiling impurity is a sort of contamination, consisting of the taints, etc. clearness in the self is the knowledge which can distinguish such things as the self (ātman). It is of this that it is now said that it is knowledge of the thing as it really is (bhūlārtha); it is a progressively clearer stage by stage corresponding to the progressive destruction of the taints and brighter very distinct light of knowledge the nature of samādhi-knowledge being extreme purity. The light is the knowledge, for by it one knows the thing as it is (yathāvastu). So it is said:
As a man on a crag sees those in the plain, so the man of knowledge,
High on the palace of knowledge beyond sorrow, looks on all the beings in their pain.