Yajnavalkya or Yagyavalkya (Sanskrit: याज्ञवल्क्य, IAST:Yājñavalkya) is a Hindu Vedic sage featuring in the Brihadaranyaka Upanishad (c. 700 BCE). Yajnavalkya proposes and debates metaphysical questions about the nature of existence, consciousness and impermanence, and expounds the epistemic doctrine of neti neti ("not this, not this") to discover the universal Self and Ātman. Texts attributed to him include the Yajnavalkya Smriti, Yoga Yajnavalkya and some texts of the Vedanta school. He is also mentioned in various Brahmanas and Aranyakas. Source: Wikipedia (en)