Kṛṣṇa says, jñānaṁ te 'haṁ sa-vijñānam (BG 7.2): "I'll speak to you about jñāna." Everyone is in ajñāna and falsely thinking that he is some very important person. This is ajñāna. Real jñāna, as will be explained here, is to receive from Kṛṣṇa. So Kṛṣṇa is giving knowledge in the Bhagavad-gītā. He'll speak in later chapters that, "The real jñāna is to surrender unto Me." This is real jñāna. Kṛṣṇa will say in the Eighth Chapter, bahūnāṁ janmanām ante jñānavān māṁ prapadyate (BG 7.19): "After many, many births." So we are . . . today I may be minister, and tomorrow, after death, I may become a dog. But that is not in my control. You cannot say that, "I am minister. I am this. I am that. I am high-court judge or very important man. So I am ordering material nature. Although I shall die, next life I shall become again high-court judge or Nārāyaṇa, something." No. That is not possible. You are fully under control. You have given a license to enjoy or suffer in this body, and in this body, as soon as it is finished, karmaṇā daiva-netreṇa jantur . . . (SB 3.31.1), and then you'll get another body.
So this jñāna, even this jñāna, that change of body is not there. Throughout the whole world, big, big professor, big, big educationist, they do not believe in the next birth—99.9%, they do not. But this is a fact. There is. Tathā dehāntara-prāptiḥ. Kṛṣṇa says. And we understand this also. Kṛṣṇa gives this example: dehino 'smin yathā dehe kaumāraṁ yauvanaṁ jarā (BG 2.13). This child is becoming kumāra; a kumāra is becoming boy, boy is becoming young man; young man is becoming old man. So these changes are going on—still, he does not know that, "After this old body is finished, I shall have to accept another body." So this is ignorance. Therefore we have to take knowledge from the most perfect Personality of Godhead, Kṛṣṇa. This is real knowledge.
So jñānaṁ te ahaṁ sa-vijñānam. Sa-vijñānam means with practical application. As there is theoretical knowledge and practical knowledge in scientific advancement, so simply theoretical knowledge will not help me. Theoretically I may know that I am not this body, but practically it must be known. If not, if I am not this body, then I am soul. Then I am working here in this world only for my body. What I am doing about my soul? That is knowledge. Suppose I have got this coat and pant and hat. If he simply tries . . . dry clean the coat and do not put any food in the stomach, how long this civilization will go on? Starving. So the whole world is in disturbed condition because there is no spiritual food, only material cleansing the shirt and coat. That is going on. Like cats and dogs, they are interested with the body.