Very nicely it is described in the Viṣṇu Purāṇa, shortly, what is this world, manifested world. This manifested world is distribution of the energy of Brahman. Just like this whole material world, universe, is distribution of the energy of the sun. This is scientific. Everyone knows. Similarly, whatever there is, it is the distribution of the energy of Kṛṣṇa. So Kṛṣṇa and Kṛṣṇa's energy not different. But still, energy is not Kṛṣṇa, Kṛṣṇa is not energy. In this way we have to understand Kṛṣṇa.
So every living entity who has forgotten Kṛṣṇa, trying to be. . . trying to imitate Kṛṣṇa, that is sinful. So these sinful activities we are doing in ignorance, in lower grade of life. Just like cats and dogs and birds and trees and the. . . they do not know; there is no capacity. They are so much covered with ignorance that a tree is standing, you cut it: there is no protest, because it is so dull. Similarly, you take the animal, slaughterhouse, it cannot protest. These are the symptoms of ignorance. And as soon as there is awakening of Kṛṣṇa consciousness or advanced consciousness, then if I pinch you, immediately you protest, "Why you have pinched me?" That is the difference between the lower-grade life and higher-grade life. So if in the higher-grade life we do not understand Kṛṣṇa, then we are making suicide, cutting our own throat. That is sinful.
So here is a chance, the human form of body. Death will come to the dog and to me also. Then where is the difference? The difference is so long I am living, I can try to understand Kṛṣṇa; others cannot. If we miss this opportunity, then we are committing suicide. This is the verdict of the śāstra. Nāyaṁ deha deho-bhājāṁ nṛloke. Everybody has got material body. The ant has got also material body, and Lord Brahmā has got also material body. Anyone who is in the material world, he has got this material body. Therefore it is called ayaṁ deha: "this deha, this body." I am not deha. That is the tenth-class ignorance if I think, "I am this body." Nāyaṁ deho deha-bhājāṁ nṛloke (SB 5.5.1). Everyone has got body, but nrloke, in the human society, the body which you have got, or the person who has got this human form of body, kaṣṭān kāmān na arhate, for such animal, I mean, having this material body, human body, it is not meant for working so hard. That is first-class civilization, when people are not working very hard; living very peacefully and getting their necessities of life. That is first-class civilization. Not that to work day and night like hogs and dog, and get a cup of tea and little morsel of bread. That is not civilization. Therefore śāstra says, nāyaṁ deho deha-bhājāṁ nṛloke kaṣṭān kāmān arhate viḍ-bhu . . . (SB 5.5.1). This kind of hard labor for sense gratification little, it is done by the hogs and dogs.
So to teach people to work day and night for simply eating purposes, sense gratification, that is hog civilization, according to śāstra. Nāyaṁ deha deho-bhājāṁ nṛloke kaṣṭān kāmān arhate viḍ-bhujāṁ ye. Then what is the purpose of human life? Tapo divyaṁ putrakā yena śuddhyed sattva yena brahma-saukhyaṁ anantam (SB 5.5.1). You are seeking after happiness. So this life is meant for tapasya, austerity, not to indulge in sense gratification. That is done by the dogs and hogs. You are human being, you are meant for practicing austerity. "Oh, why shall I practice austerity?" Now, yato śuddhyed sattva: your existence will be purified. You are suffering in this material world because your existence is not purified. Therefore you are accepting death. Who dies? The diseased man dies. Of course, everyone dies. Everyone is diseased here. But generally, we understand, one who is not healthy, he dies. So why we die? We are eternal. Everyone knows. Nityaḥ śāśvato 'yam na hanyate hanyamāne śarīre (BG 2.20). Then why I am dying? Why I am suffering from disease, from old age? This should be the human question, and they should try to solve this, and this opportunity is given by nature and God combined. God has ordered nature to give me this machine, human form of body. If we do not utilize it as human being, that is sinful. That is sinful.