The witness of the three states of consciousness [waking, dream and deep sleep] and of the nature of Existence-Consciousness-Bliss is the Self
All the manifested world of things and beings are projected by imagination upon the substratum which is the Eternal All-pervading Vishnu, whose nature is Existence-Intelligence; just as the different ornaments are all made out of the same gold.
From a clear knowledge of the Bhagavad-gita all the goals of human existence become fulfilled. Bhagavad-gita is the manifest quintessence of all the teachings of the Vedic scriptures.
Thus one should know oneself to be of the nature of Existence-Consciousness-Bliss [Sat-Chit-Ananda].