Devotee: Verse 11: "The Blessed Lord said: While speaking learned words you are mourning for what is not worthy of grief. Those who are wise lament neither for the living nor the dead (BG 2.11)." Purport: "The Lord at once took the position of a teacher and chastised his student, calling him indirectly a fool. The Lord said, 'You are talking like a learned man, but you do not know that one who is learned, one who knows what is body and what is soul, does not lament for any stage of the body, neither in the living nor in the dead condition.' As explained in the later chapters, it will be clear that knowledge means to know matter and spirit and the controller of both. Arjuna argued that religious principles should be given more importance than politics or sociology, but he did not know that knowledge of matter, soul and the Supreme is more important than religious formularies. And because he was lacking in that knowledge, he should not have posed himself as a very learned man. As he did not happen to be a very learned man, he was consequently lamenting for something which was unworthy of lamentation. The body is born and is destined to be vanquished today or tomorrow. Therefore the body is not as important as the soul. One who knows this is actually learned. For him there is no cause for lamentation in any stage of the material body."
Prabhupāda: He says, Kṛṣṇa says, that "This body, either dead or alive, has nothing to be lamented." Dead body, suppose when the body is dead, it has no value. What is the use of lamenting? You can lament for many thousands of years, it will not come to life. So there is no cause of lamenting on dead body. And so far spirit soul is concerned, that is eternal. Even it appears to be dead, or with the death of this body, he does not die. So why one should be overwhelmed, "Oh, my father is dead, my such and such relative is dead," and crying? He's not dead. This knowledge one must have. Then he'll be cheerful in all cases and he'll be interested simply in Kṛṣṇa consciousness. There is nothing to be lamented for the body, either alive or dead. That is being instructed by Kṛṣṇa in this chapter. Go on.
Devotee: "Never was there a time when I did not exist, nor you, nor all these kings. Nor in the future shall any of us cease to be (BG 2.12)." Purport: "In the Vedas, in the Kaṭha Upaniṣad, as well as in the Śvetāśvatara Upaniṣad, it is said that..."
Prabhupāda: (correcting pronunciation) Śvetāśvatara. There are many Upaniṣads, they are called Vedas. Upaniṣads are the headlines of the Vedas. Just like in a chapter there is a headline, similarly these Upaniṣads are the headlines of the Vedas. There are 108 Upaniṣads, principal. Out of that, nine Upaniṣads are very important. So out of those nine Upaniṣads, Śvetāśvatara Upaniṣad, Taittireya Upaniṣad, Aitareya Upaniṣad, Īśopaniṣad, Īśa Upaniṣad, Muṇḍaka Upaniṣad, Māṇḍūkya Upaniṣad, Kaṭhopaniṣad, these Upaniṣads are very important. And whenever there is argument on some point, one has to give reference from these Upaniṣads.