Vijñānamaya-kośa

Sheath made of discernment

The sheath of buddhi — discriminative knowing, the witness-near intelligence that decides, doubts in a higher register, and resolves. Taittirīya II.4 places it inside the manomaya, with the same shape; it is the agent of yajña — every act becomes a sacrifice once buddhi is awake. In Advaita this is the sheath most easily mistaken for the Self, because its clarity feels like presence itself. The teaching insists: even buddhi is an object lit by the witness — it sleeps in deep sleep, the witness does not.