The witness of the three states of consciousness [waking, dream and deep sleep] and of the nature of Existence-Consciousness-Bliss is the Self
Adi ShankaraDo not look at anybody in terms of friend or foe, brother or cousin; do not fritter away your mental energies in thoughts of friendship or enmity. Seeking the Self everywhere, be amiable and equal-minded towards all, treating all alike.
Adi ShankaraFrom 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.
Adi Shankara