Devotee: Translation, "Now please hear My brief description of this field of activity and how it is constituted, what its changes are, whence it is produced, who that knower of the field of activities is, and what his influences are."
Prabhupāda: Tat kṣetram (BG 13.4). Idaṁ śarīraṁ kaunteya kṣetram ity abhidhīyate (BG 13.2). So Kṛṣṇa has already explained, kṣetra means idaṁ śarīram. Śarīram means this body. Tat kṣetram. First of all, you have to understand that this body or any field of action, anywhere, the three things are there: the field of activities, the owner of the field and the supervisor of the field. You can check and tally anywhere. So Kṛṣṇa says kṣetra-jñaṁ cāpi māṁ viddhi. There are two kṣetrajñaḥ and one kṣetra. One field of activity and two personalities, kṣetrajñaḥ. One is to be supposed as occupier and the other is supposed to be the owner.
Just like in this house we are occupier. The house is kṣetra, field of activities. The landlord is the owner and we are the occupier. Two kṣetrajñaḥ. This property is interest for two persons. One is the occupier and the other is the owner. Similarly, anywhere, any part of the world, anywhere you go, you will find these three things: One, the field of activities and the other two means one occupier and one owner. If one understands these three things and he can study everywhere these three things, then: kṣetra-kṣetrajñayor yad jñānam. This knowledge, to understand everywhere that there is a field of activity and two persons are interested in that field of activity... One is the owner, another is the occupier. If you study these three things only, then: taj-jñānaṁ jñānam. That is knowledge. Otherwise all rascals and fools, that's all. Mataṁ mama. (aside:) Don't sit like that.
This is jñānam. But ask anybody at the present moment who is the owner, who is the occupier and what is the field of activities. If you ask three things, nobody will be able to answer. That means everyone is rascal at the present. Or they do not know. Kṣetra-kṣetrajñayor yaj-jñānam, Kṛṣṇa says, "This relationship between the field of action, and the owner."
Just like in agriculture. The land is owned by the state or the king. And it is rented or occupied by somebody else. And the land is the field of action. So Kṛṣṇa is giving direction. Kṛṣṇa is giving direction, and the living entity is there. He is acting according to that direction.
So both Kṛṣṇa and the living entity are sitting in one tree. That is stated in the Upaniṣad. Two birds are sitting in one tree. One is eating the fruit of the tree and other is simply witnessing. The witnessing bird is Kṛṣṇa. And the bird who is eating the fruits of the tree, he is the living entity. The Māyāvādī philosophers, they cannot distinguish between the jīva soul, jīvātmā, and Paramātmā. They know it, but because they are monists, to establish their theory, they say there is no two, there is one. No. Kṛṣṇa says two. One kṣetrajñaḥ, the jīvātmā, and the other kṣetrajñaḥ He is, Kṛṣṇa. The difference between the two is that the individual living entity knows only about his kṣetra, body, but the other living entity, the supreme living entity, He knows all the bodies.