Kośa

Kośa means 'sheath' — that which covers. Taittirīya Upaniṣad 2 presents the pañca-kośa, five concentric sheaths covering ātman: annamaya (food/physical body), prāṇamaya (vital), manomaya (mental), vijñānamaya (intellectual), ānandamaya (causal). The sheath-by-sheath analysis is a method of inquiry: each koṣa is identified, examined, and recognized as non-ātman. What remains after negating all is ātman.