There are two persons in this world — the perishable and the imperishable. All beings are the perishable; that which stands immovably at the summit is called the imperishable.

Krishna introduces the philosophical framework for the chapter's climactic teaching. Two great categories of existence: the kṣara (perishable) — all embodied beings, all manifestations that come into form and pass away — and the akṣara (imperishable) — the unmanifest, the kūṭastha, the one who stands unmoved at the summit of all existence, like an anvil on which all change is hammered without itself being deformed. This second category is often understood as māyā-śakti or the unmanifest Prakriti — the totality of the potential from which all manifestation arises. Both are real; both are categorically distinct. But there is a third category — beyond both — which this teaching is building toward.