So kāla's business is—kāla, time—to kill. So here also it is said, sa kālena iha, kālena mahatā. Mahatā is also kāraṇa, and kālena, by the influence of . . . that is now lost. Because it is a struggle. Our struggle for existence means we are trying to exist, but kāla is fighting to kill. That is going on. So kāla's business, time's business is to kill, but that system is now lost, is now killed by the influence of time. Sa kāleneha . . . yogo naṣṭaḥ parantapa.
Then, what is to be done? Sa eva ayaṁ mayā te adya yogaḥ proktaḥ purātanaḥ (BG 4.3). "So I have already begun to teach you about this Bhagavad-gītā. So it is not a new doctrine that I'm presenting before you." That, called . . . sa eva ayaṁ mayā te 'dya yogaḥ proktaḥ purātanaḥ. Purātanaḥ means the same old system, purātana. Purātana means purāṇa. Purāṇa means the old, historical events. Purāṇa. And this Mahābhārata, Mahābhārata is also . . . Mahābhārata, great history. And the Śrīmad-Bhāgavata is also called Mahā-Purāṇa, the great history of olden days.
So here also, the same word is used, that Kṛṣṇa says sa eva ayam: "This yoga system, the Bhagavad-gītā yoga system which I am now speaking to you, is very old. How old you can imagine, that I first spoke it to the sun-god." If you calculate only the age of Manu, it is about forty millions of years ago, to speak the minimum. So anyway, it is very, very old. Not that it is doctrine which is presented . . .
Just like in the modern educational system somebody is presenting some doctrine, and he's getting the title "Doctor," some new thesis. It is not like that. There is nothing to be researched. Eternal knowledge has nothing to be researched. There is no question of research. It is already established. Otherwise there is no meaning of eternal.
So this knowledge of Bhagavad-gītā is eternal. It is not a product of modern research or doctrine. Purātanaḥ sa eva. Sa evāyaṁ mayā te adya. Adya means "today." "Today I am speaking on the battlefield." Yogaḥ proktaḥ purātanaḥ.
"Why You are selecting me? Why You are selecting me and why this battlefield? You are speaking a philosophical doctrine and the science of God, and You are speaking to me. I am not a Vedāntist, I am not even a brahmin, I am not even sannyāsī. Ordinary gṛhastha. Of course, I have got the privilege that I am Your friend. So much so. Otherwise, yoga system is not to be spoken to me. Why You are speaking to me?" This may be questioned. Why specifically it was spoken to Arjuna? The reply is, bhakto 'si: "The only qualification is that you are My devotee. That's all."
Therefore from the very beginning it is to be understood one who is not a devotee of Kṛṣṇa, he cannot understand what is Bhagavad-gītā. Those who are not devotees . . . there are different classes of men. Some of them are karmīs, some of them are jnānīs, some of them are yogīs and some of them are bhaktas. The enlightened, cultivated persons, they can be divided into four groups. Those who are ordinary men, they do not know anything except to keep this body comfortably. They're materialistic, more or less. In this life or next life they simply want material comfort. They are called karmīs.
And jnānīs . . . jṣānīs means who are disgusted with this karma. Because there is a time, a point, when they become disgusted. Just like the American young men, they are now disgusted with this material civilization. So they are searching after knowledge. But unfortunately, the state is also not very enthusiastic, and there are many who are exploiting. But here is the knowledge. And that point comes, when the karmīs become disgusted, confused. Because the spirit soul, he wants spiritual life. He cannot be happy with any amount of materialistic life.
In our childhood we read one poetry that a boy has brought one bird, and the bird is talking with the boy. "My dear bird, you live with me. I shall give you very nice food. I shall talk with you," and so many things. But the bird says: "No, I want to go away. I want to go away." "No, I shall give you golden cage. You don't go away." So he says: "No, no. I don't like golden cage. I want freedom." So that was talk. So similarly, if a bird is kept in golden cage and if golden foodstuff is supplied to him, it is not happy. It is not possible.