This human life is a gift by the nature or by God. Now you realize that you are changing your different condition, distress and happiness, being forced to accept some kind of gross and subtle body. That is the cause of your pains and pleasure. And if you get out of this gross and subtle body, remain in your original, spiritual body, then you are free from these pains and pleasure. That is called mukti. Mukti, there is a Sanskrit word. Mukti means liberation: no more gross body, no more subtle body, but you remain in your own original, spiritual body. This is called mukti. Mukti means . . . it is described in the Bhāgavatam, muktir hitvā anyathā rūpaṁ sva-rūpeṇa vyavasthitiḥ (SB 2.10.6). That is called mukti. Anyathā rūpam. Anyathā rūpam means in otherwise, staying or living in otherwise. Otherwise means that I am spirit soul. I have got spiritual body. But some way or other, circumstantially, on account of my desire, I get sometimes human body and sometimes dog's body, sometimes cat's body, sometimes tree's body, sometimes demigod's body. There are different . . . 8,400,000 different forms of body. So I am changing according to my desire. And according to my infection, kāraṇaṁ guṇa-saṅgaḥ asya (BG 13.22), and according to my . . . these are the subtle things.
That is the real knowledge of human being, not to invent something for temporary happiness. That is foolishness. That is foolishness, wasting time. If we invent something for the comforts of this present body and I shall live very comfortably, but "You will not be allowed, sir, to live comfortably." First of all you know it. Suppose a man is constructing very nice house, very strong house, it will never fall down in any circumstances. But that's all right, but what you have done for yourself that you will never die so that you will enjoy this? "No. Let it be. Let me have a very strong-built house." So house remains. You go there. Strong-built nation. Just like Napoleon constructed strong-built arches, but where he has gone, nobody knows. So therefore Bhaktivinoda Ṭhākura says, sings, jaḍa-bidyā sab māyāra vaibhava tomāra bhajane bādhā. The more we advance in so-called material happiness or material advancement, the more we forget our real identity. This is the result.
So we should understand that we have got a separate business, real business. That is called self-realization that, "I am not this body." This is self-realization. That is being instructed by Kṛṣṇa in the beginning that, "You are not this body." The first understanding, first knowledge, is to understand that, "I am not this body; I am spirit soul. I have got a different business." It is not that this temporary actions or activities like as a dog or as a human being or as a tiger or as a tree or as a fish, there are activities. Āhāra-nidrā-bhaya-maithunaṁ ca (Hitopadeśa). The same principle of bodily necessities: eating, sleeping, sex life and defense. But in the human form of life, I have got a separate business, self-realization, to get out of this bodily entanglement. And that is called knowledge.
Without this knowledge, anything we are advancing in knowledge, that is foolishness, that's all. Śrama eva hi kevalam (SB 1.2.8). Śrama eva hi kevalam. Śrama eva hi kevalam means simply working uselessly and wasting time. You cannot check the nature's law. Suppose in this life you are very big leader, prime minister, and everything. That's all right, but according to your mentality, you are creating next life. So in this life you remain a prime minister, and in next life you become a dog. Then where is the benefit? There is not . . . therefore these atheist fools, they want to deny next life. That is very horrible for them. That is very horrible to them. If they accept next life . . . they know their life is very sinful. Then what life they are going to get by the laws of nature? When they think of it, they shudder. "Better deny it. Better deny it." Just like a rabbit. Enemy is in his front, and he is going to die, but he thinks, "Let me close my eyes, I am out of danger."
This is atheistic view, that they are trying to forget that there is . . . therefore they deny, "There is no life." Why not? Kṛṣṇa says that "You had a childhood body. You had a baby . . . now you have . . . where is that body? You have left that. You are in different body. Similarly, this body you'll change. You will get another body." And who says? Kṛṣṇa says. The most superior authority, He says. I may not understand, but when He says . . . this is the process of our knowledge.