Arjuna inquired from Kṛṣṇa six things: kṣetra, kṣetrajña, prakṛti, puruṣa, jñānam, jñeyam. What is knowledge and what is the object of knowledge, jñānam jñeyam. And kṣetra, field of activities; kṣetrajña, the worker on that field; kṣetra, kṣetrajña and prakṛti, nature—and the puruṣa. Material nature and puruṣa means the enjoyer. Six question. Of course, Bhagavad-gītā is, each and every word and letter, is full of knowledge. But these six inquiries, if actually can understand the six items, he becomes the perfect knower. That is said by Kṛṣṇa: yat taj jñānaṁ mataṁ mama. Jñānam means knowledge. So if anyone can understand the six items, then he is in full knowledge.
Yat taj jñānaṁ mataṁ. "You have asked Me, Arjuna . . ." and bhagavān uvāca, and the Supreme Personality of Godhead speaking. Not only speaking; He says, just like a gentleman . . . whatever He says is perfect, but still He says: "This is My opinion." "This is My opinion." Now my opinion you can take or not take, that is up to you. But who can give better opinion than Kṛṣṇa? That is another knowledge. Why Kṛṣṇa? Arjuna is asking Kṛṣṇa. Because in the beginning he has said that, "Nobody can make solution of my problem. You are the best." So following the footsteps of Arjuna, if we accept Kṛṣṇa's words, not blindly but with good logic, good scientific research, if we actually try to understand what Kṛṣṇa speaks, then all our problems are solved.