This material world, composed of many millions of universes, that is one-fourth creation of the Supreme Personality of Godhead. Ekāṁśena sthito jagat.
So Bhagavad-gītā means to understand what is God, the science of God. And God Himself is speaking about Himself. Otherwise it is not possible to understand what is God. So if we carefully understand the ślokas and the passages mentioned in the Bhagavad-gītā, we can understand what is God. And the human form of life is meant for understanding God. He has no other business. In the lower bodies, less than human form of body... According to Darwin's theory, the human form of body comes from monkey. But the evolution is accepted in the Vedic literature but not like Darwin's. The evolution, again according to Vedic scripture, is that the living entity is different from the body, and the living entity is passing through many forms of body. We shall read that. So the bodies are according to my desire. I am desiring something. Just like here we are sitting, so many ladies and gentlemen, but not one of them is similar to anyone else. They have got different bodies. That body is created according to one's desire. The mind, the subtle mind, is the creator of the next body. Yaṁ yaṁ vāpi smaran bhāvaṁ tyajaty ante kalevaram (BG 8.6). At the time of death whatever I am thinking, a similar body will be offered to me by the laws of nature. Subtle body. The mind, intelligence and ego, they are subtle body, and the gross body is made of earth, water, air, fire, ether. So when we give up this gross body, the subtle body carries me to another gross body. This is the way of transmigration of the soul. The prakṛti, nature, nature's law, is very strict and stringent. The nature will immediately offer you a similar body according to the thinking at the time of your death. Tathā dehāntara-prāptiḥ (BG 2.13).
Therefore this human form of body is meant for going back to home, back to Godhead. Yad gatvā na nivartante tad dhāma paramaṁ mama (BG 15.6). We are eternal. As God is eternal, we are also eternal because we are part and parcel of God. As God is always blissful, jolly, similarly our nature is always blissful and jolly. Sac-cid-ānanda-vigrahaḥ (Bs. 5.1). Sat, cit, ānanda. Sat means eternal, and cit means blissful, cit means full of knowledge; and ānanda. Ānanda means blissfulness. That is our nature. Therefore we want to live. We do not wish to die. We do not wish... Nobody wishes to die, but we are forced to die. That is our punishment. Nityaḥ śāśvato 'yaṁ na hanyate hanyamāne śarīre (BG 2.20). This instruction you will get in the Bhagavad-gītā, that "The living entity is eternal," śāśvata, "very, very old." Nityaḥ śāśvato 'yaṁ na hanyate hanyamāne śarīre: (BG 2.20) "When the body is destroyed, is annihilated, the soul exists. It goes to another body." The example is just like every one of us... In the first day of intercourse of the father-mother, the secretion mix together, emulsified, and if the living entity is allowed to enter into that, it grows. That is the beginning of our body. But if the living entity is not allowed into the, that emulsified, small pealike form, then there is no pregnancy. So attempt is made to pollute that emulsification. Therefore the living entity cannot enter into it and there is no pregnancy. Otherwise there must be pregnancy. Then that pealike body grows, and in seven months it grows the hands and legs and head and everything, and consciousness comes back. When we die our consciousness becomes almost stopped, and we then lie down within the womb of the mother according to species of body, a status—take it for granted our human form of body—seven months. At that time body is grown up. In this way, in tenth month the body is fully grown. Then by nature's way the body comes out and another life begins. This is called transmigration of the soul.
So actually we are eternal. In the Vedic language it is said, nityo nityānāṁ cetanaś cetanānām eko yo bahūnāṁ vidadhāti kāmān (Kaṭha Upaniṣad 2.2.13). Nitya. Nitya means eternal. And nityānām. Nityānām means plural number of nityas. So there are many nityas, means many living entities, but there is one nitya Supreme. That is God. He is also a living entity like us. Then where is the difference? The difference is, we learn from the Vedic line, eko bahūnāṁ vidadhāti kāmān: "That singular number nitya, eternal, maintains the plural number nityas." We are within the plural number, nityānām. So conclusion is that God is the Supreme Being and we are living being. So our relation is very intimate. Qualitatively we are one because we are part and parcel. So God is eternal, full of knowledge, and blissful; therefore our position is also the same but in minute quantity. His knowledge is great. Therefore God is great. Our knowledge is limited. And because we have got limited potencies, therefore we are called living entities. And God has got unlimited potencies, therefore God is great and we are small. This is conclusion of the Bhagavad-gītā. And we are in this material world being contaminated by the material nature. We are suffering because anything material, it has got limited period of existence. Anything you take, it is asat. Asat means "which will not exist," and sat means "which will exist." The Vedic injunction is asato mā sad gama: "You are sat. You revive your eternal life. Don't be entangled in this asat."