Simply we must have brain to understand. Mayā tatam idaṁ sarvam. Every particle, every atom, there is presence of God. That is stated in the śāstra. Aṇḍāntara-stha-paramāṇu-cayāntara-stham (BS 5.35). Paramāṇu means the atom. God is within the atom. So God is within you also. God is outside; God is within. Outside, as we see these five elements. What are these five elements? The same thing: expansion of God's energy. Just like we practically see scientifically, the sunshine is the cause of this universe. Within the sunshine all the planets have grown, and in each and every planet, due to the sunshine the vegetables are growing, there are leaves. When there is no sunshine the leaf falls down. As soon as the sunshine is there, the colorful fruits and flowers and leaves come out. Everything is due to the sunshine.
Similarly, the supreme sun is Kṛṣṇa. Yasya prabhā prabhavato jagad-aṇḍa-koṭi (BS 5.40). He has got . . . Just like the sun has shining, similarly—try to understand—God has got His effulgence, bodily shining. That is called brahma-jyoti. When the brahma-jyoti is there, innumerable universes are generated. Therefore He is cause of all creation. It doesn't require to manufacture each and every universe. He is so powerful that in His effulgence, in His shining, innumerable universes are created. Yasya prabhā prabhavato jagad-aṇḍa-koṭi-koṭiṣv aśeṣa-vasudhādi-vibhūti-bhinnam (BS 5.40). In each universe there are many millions and millions of stars and planets. These are the description in the Vedic literature.
So we have to learn. You cannot by your teeny effort with limited power, limited sense, I mean to say, perception, you cannot speculate. You have to understand from authoritative statements. That is called Veda. Vedas means knowledge which is perfect knowledge, and if you study Vedas, then you get perfect knowledge of everything. And the cream of the Vedic knowledge is here in the Bhagavad-gītā. So if you read Bhagavad-gītā carefully, then you get all the knowledge very perfectly. Here it is said, mayā tatam idaṁ sarvaṁ jagad avyakta-mūrtinā. And that expansion, that impersonal expansion, avyakta, not manifested. You cannot see God in person in this expansion. Therefore sometimes we foolishly say that "Can you show me God?" God is there. You have to make your eyes to see. Just like God is here in the temple, but somebody is thinking that "This is not God. This is a statue or an idol. They are worshiping idol." Supposing it is idol, but if God is everywhere, why He is not in the idol? What is the argument? If God is everywhere, then why He is not idol? God has the power. And actually this is not idol; this is God's energy. The same example: the sunshine is everywhere, so originally sunshine is the cause of everything. Similarly, God's effulgence is the cause of material things also.