Śivasaṃhitā 1.53

Self-luminosity as the defining characteristic of Spirit. Unlike the sun, which illuminates other objects but requires space to manifest, Spirit needs no external agent to be known. It knows itself. This is why deep meditation does not seek to illuminate the ātman, but to cease the obscuration that prevents seeing it.

The term svaprakāśa (self-luminous, illuminating itself) is one of the most important technical descriptors of brahman in Vedānta. It stands opposed to paraprakāśa (illuminated by another), the category to which all worldly objects belong. Space (ākāśa) has no light of its own; Spirit does. Samantataḥ (in all directions) underscores the isotropy of that presence.

The doctrine of self-luminous knowledge (svaprakāśa) has profound epistemological implications: if Spirit knows itself, what role does the seeker play? In the Śivasaṃhitā, yogic practice does not create knowledge of the ātman, but eliminates the veils that obscure it. The yogi does not reach the light: they recognize that they always were that light.