Śrīmad-Bhāgavatam 7.9.35
—
Māyāpur, March 13, 1976
So we have to undergo tapasya because our grandfather, he had to undergo tapasya. So anyone who is in this material world, Brahmā, beginning from Brahmā down to the ant, must undergo tapasya. But for the ant, cats and dogs, it is not possible. They are condemned. They will have to come to the human form of life by evolutionary process by the help of nature. But as soon as we come to the human form of life, the responsibility is there. What is that responsibility? Because you have got developed consciousness more than the cats and dogs, you have to decide, "How I have come to this material world? Why I am suffering? I do not wish to die. The death is there. I do not want disease. The disease is there. I don't want to take birth, enter into the womb of the mother. Still I am forced to do it. I don't want to become an old man. I become old man." So this is human intelligence. Unless you come to this intelligence, athāto brahma jijñāsā, "What I am? Am I this body or something else...?"
So we have to analyze, analyze that this body is made of the material elements: earth, water, fire, ether, like that. The... We are breathing. What is this breathing? We are very much proud of breathing. Eh? The breathing is simply ventilation, air. But you cannot set up this breathing to a dead man. That is not possible, although it is simply air, nothing but air. But as soon as it is gone out of it... You are great scientist. Bring this air, pump. No, there is no life. So in this way there is analysis. From water we are getting blood. From blood we are getting semina. From urine... So many things we are getting. So this body is manufactured by these things, by the material elements. So am I this body? If I am this body, then after the death why...? These material elements are there. Why you cannot replace it? I am not body. I'm living within the body. And that is confirmed in the Bhagavad-gītā. Kṛṣṇa says, dehino 'smin yathā dehe kaumāraṁ yauvanam, tathā dehāntara [Bg. 2.13]. Asmin dehe: "In this body there is the living entity."