With this shloka, the final section of Chapter 15 begins.

From 15.7 to 15.15, Bhagavān taught Brahmaṇaḥ sarvātmakatvam — Brahman alone appears as everything. From 15.7 to 15.11, Brahman was shown as the jīva in living beings. From 15.12 to 15.15, Brahman was shown as the jagat, the entire universe, through examples such as sun, moon, fire, earth, plants, digestion, memory, knowledge, and the Vedas. That section concluded with the teaching that Bhagavān is in everything and is everything.

Now, in 15.16–15.18, Bhagavān defines the title word of the chapter: Puruṣottama. The chapter is called Puruṣottama-yoga, and now Bhagavān explains what Puruṣottama means. First, in 15.16, He presents two puruṣas: kṣara-puruṣaḥ and akṣara-puruṣaḥ. Then, in 15.17, He will introduce the third, uttama-puruṣaḥ, which is Puruṣottama, nirguṇa caitanyam.

The shloka says: dvau imau puruṣau loke — in this world, there are these two puruṣas. Here puruṣa should not be taken as a male person. It means a fundamental principle or category. Bhagavān is dividing the entire experienced world into two material categories first.

The first is kṣaraḥ. The word kṣara means that which perishes, changes, decays, flows away, or is subject to modification. Bhagavān says: kṣaraḥ sarvāṇi bhūtāni — all beings, all manifest things, are kṣara. Swami explains this as the entire visible, manifest matter. Everything we can objectify — body, mind, sense organs, objects, planets, stars, plants, animals, elements, and all visible matter — comes under kṣara-puruṣaḥ. It is perishable not only because it finally disappears, but because it is changing every moment.

The physical body is kṣara. The mind is also kṣara. Thoughts arise and disappear. Emotions come and go. Memories change. The body of a child becomes the body of an adult, then becomes old. Mountains appear stable, but they too change over time. Even the sun, moon, and stars belong to the changing manifest order. Therefore sarvāṇi bhūtāni means the entire manifest universe, not merely living beings.

The second is akṣaraḥ. The word akṣara means imperishable. But here we must be very careful. In this verse, akṣara does not mean Brahman. It does not mean the absolute, changeless consciousness. It means unmanifest matter, māyā-tattvam, the causal condition of the universe. Swami explicitly warns that the word kūṭasthaḥ can be misleading, because in other chapters it has a different meaning. In this context, kūṭasthaḥ means unmanifest matter, māyā. It is called akṣara because it is relatively eternal compared to the changing manifest universe.

A simple way to understand this is through the relation between seed and tree. The tree is visible, changing, and perishable. It represents the manifest condition. But before the tree appears, it exists in an unmanifest seed-condition. That seed-condition is not absolutely permanent, but compared to the visible, changing forms, it is subtler and more enduring. Similarly, the entire manifest universe arises from unmanifest matter and resolves back into it. The manifest matter is kṣara; the unmanifest causal matter is akṣara.

This shloka is not yet presenting consciousness as the final reality. It is preparing the ground. First Bhagavān says: there is manifest matter and unmanifest matter. Both are still matter. Both are acētana, inert. Both are saguṇa, associated with attributes. Both belong to the material order. In 15.17, Bhagavān will introduce the third principle, the consciousness principle, which is different from both. Swami’s explanation of the threefold division is: manifest matter, unmanifest matter, and consciousness. The first two are matter; the third alone is caitanyam, independent consciousness.

So 15.16 is a classification verse. It says: before understanding Puruṣottama, first understand what Puruṣottama is not. Puruṣottama is not the changing manifest universe. Puruṣottama is also not the unmanifest causal māyā. These two are kṣara and akṣara puruṣas. The next verse will reveal the uttama-puruṣaḥ, the consciousness that is beyond both.