What is enquiry into the Truth? It is the firm conviction that the Self is real, and all, other than That, is unreal.
Adi ShankaraThe witness of the three states of consciousness [waking, dream and deep sleep] and of the nature of Existence-Consciousness-Bliss is the Self
Adi ShankaraJust as a stone, a tree, a straw, grain, a mat, a cloth, a pot, and so on, when burned, are reduced to earth (from which they came), so the body and its sense organs, on being burned in the fire of Knowledge, become Knowledge and are absorbed in Brahman, like darkness in the light of the sun.
Adi Shankara