Sanskrit
द्वाविमौ पुरुषौ लोके क्षरश्चाक्षर एव च । क्षरः सर्वाणि भूतानि कूटस्थोऽक्षर उच्यते ॥
dvāv imau puruṣau loke kṣaraś cākṣara eva ca kṣaraḥ sarvāṇi bhūtāni kūṭastho 'kṣara ucyate
Translation
There are two Energies in this world, the destructible and the indestructible; the destructible is all beings, the unchanging is called the indestructible.
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
The chapter’s technical core begins with a formal taxonomy: two Purushas exist in the world, kshara (the perishable, identified with all beings) and akshara (the imperishable, called kūṭastha — literally “standing at the peak,” meaning unchanging, like an anvil). This binary maps roughly onto the field/knower-of-the-field distinction chapter 13 spent its length developing, but restates it in starker, more classificatory language, setting up the third term — the Purushottama — that verses 17-18 will introduce to break the binary open.