Bhagavad Gita 15.16
द्वाविमौ पुरुषौ लोके क्षरश्चाक्षर एव च । क्षरः सर्वाणि भूतानि कूटस्थोऽक्षर उच्यते ॥
dvāv imau puruṣau loke kṣaraś cākṣara eva ca | kṣaraḥ sarvāṇi bhūtāni kūṭa-stho 'kṣara ucyate ||
Translation
There are two persons in the world, the perishable and the imperishable. The perishable is all beings; the unchanging is called the imperishable.
Reflection
Within one breath, what changes and what does not?
Read this verse in its chapter: Chapter Fifteen
Inventory before the punchline. Two persons account for everything visible and invisible. Kshara is the entire procession of beings, mortal because changing. Akshara is the kuta-stha, fixed at the anvil, the steady substrate behind every appearance. Most metaphysical maps stop here, with a binary of changing and unchanging. Verse names the binary clearly so the next verse can break it. Beginner instruction is simple. For one breath today, watch a fact in the world that is changing. For the next breath, find what in that watching has not changed. Both are real. Both are named. Neither is the last word.