Yoga Sūtra Chapter Four verse 19

न तत्स्वाभासं दृश्यत्वात् ॥१९॥

na tat-svā-bhāsaṃ dṛśyatvāt ||19||

That, not own luminosity,
due to the quality of the seen.

na - no; not; nor, neithertat - that, thissva - own; one's self, one's own, my own, thy own, his own, her own, our own, their ownbhāsa - luminosity, light, lustre, brightnessdṛśyatva - the quality of the seen; visibility, vision, sight

Commentaries and Reflections

Commentary by S Ramaswami:

“Puruṣa is said to be self-illuminating. Citta is not self-illuminating as it is an object or part of the seen.
It does not have the capacity to be self-illuminating.
It is that which appears to have consciousness. Thus, it is like the sense organs.
The question might be asked as to why the mind should not be regarded as self-luminous since it knows the feelings arising in it.
If you say that feelings are known…”