Bhagavad Gita Chapter 2, Verse 16

नासतो विद्यते भावो नाभावो विद्यते सतः | उभयोरपि दृष्टोऽन्तस्त्वनयोस्तत्त्वदर्शिभिः ||

nāsato vidyate bhāvo nābhāvo vidyate sataḥ ubhayor api dṛṣṭo 'ntas tv anayos tattva-darśibhiḥ

The unreal has no being; the real never ceases to be. The truth about both has been perceived by the seers of reality.

Arjuna's grieving over death, so Krishna cuts to the root: what's actually real? 'Asat' (the unreal) is everything that changes—your body, relationships, circumstances. These continuously transform and dissolve. 'Sat' (the real) is consciousness itself, the awareness witnessing all change. This never ceases. The 'tattva-darśibhiḥ' (seers of truth) aren't mystics but anyone investigating reality deeply—scientists studying consciousness included. Krishna's radical claim: only what never changes is truly real. Everything else is appearance, not being itself. This isn't denying the world exists; it's clarifying its nature. Your body exists now but won't forever. Your awareness? According to this teaching, always has and always will. This distinction between the eternally real and temporarily manifest is the Gita's philosophical foundation.