The first thing is that bhagavān uvāca. These things required for purification. Sattva-saṁśuddhiḥ. The human life is meant for sattva. Sattva. Sattva means existence. We are existing. I am existing; you are existing. But we are sometimes appear to be not existing. That is called death. We, every living entity, we are eternal. That is stated in the Second Chapter, that ajo nityaḥ . . . ajo nitya śāśvataḥ, na hanyate hanyamāne śarīre (BG 2.20). These things required to understand, that "I am a living being—not only I am, everyone. We are eternal, nityaḥ śāśvataḥ." There are so many universities all over the world and so-called scientists and philosophers, but they do not know that we are eternal. Just see their knowledge, advancement of knowledge. Eternal, aja. There is no birth. Na hanyate hanyamāne śarīre (BG 2.20). After this destruction of this body, I am not finished. I still exist.
What is the destruction of this body? Death means it is a machine. It is called machine. Yantrārūḍhāni māyayā (BG 18.61). It is a machine given to me. Just like you take a car. That is a machine. Now some way or other, if the car stops, not working, does it mean that you are finished? No. I can take another car. This is knowledge.