So definition by negation. Directly we cannot appreciate what is that spiritual fragment, particle, which is within this body. Because the length and breadth of that spirit soul is impossible to be measured by our material instruments, although the scientists say that we can measure it. Anyway, even it is possible, first of all, you have to see where the soul is situated. Then you can attempt to measure it. First of all, you cannot see even. Because it is very, very small, one ten-thousandth part of the tip of the hair. Now, because we cannot see, by our experimental knowledge we cannot appreciate; therefore Kṛṣṇa is describing the existence of the self soul in a negative way: "It is not this." Sometimes when we cannot understand, the explanation is given: "It is not this." If I cannot express what it is, then we can express in a negative way that "It is not this." So what is that "not this"? The "not this" is that "It is not material." The spirit soul is not material. But we have got experience of material things. Then how to understand that it is the negative? That is explained in the next verse, that nainaṁ chindanti śastrāṇi (BG 2.23). You cannot cut, the spirit soul by any weapon, knife, sword, or thistle (pistol?). It is not possible. Nainaṁ chindanti śastrāṇi. The Māyāvāda philosophy says that "I am Brahman. Due to my illusion, I feel I am separated. Otherwise I am one." But Kṛṣṇa says that mamaivāṁśo jīva-bhūtaḥ (BG 15.7). So does it mean that the, from the whole spirit, this fragment has been separated by cutting into piece? No. Nainaṁ chindanti śastrāṇi (BG 2.23). It cannot be cut into pieces. Then? Then the answer is that the spirit soul fragment is eternal. Not that by māyā it has become separated. No. How it can be? Because it cannot be cut into pieces.
If I say... Just like they put the arguments: ghaṭākāśa-poṭākāśa, that "The sky within the pot and the sky outside the pot, on account of the wall of the pot, the sky within the pot is separated." But how it can be separated? It cannot be cut into pieces. For argument's sake... Actually, we are very, very small particle, molecular parts of the spirit. So... And they are eternally part. Not that circumstantially it has become part, and again it can join. It can join, but not that in a homogeneous way, mixed-up way. No. Even it is joined, it, the soul keeps his separate existence. Just like a green bird, when he enters into the tree, it appears that the bird is now merged into the tree, but it is not that. The bird keeps its identity within the tree. That is the conclusion. Although both the tree and the bird being green, it appears that the bird is now merged into the tree, this merging does not mean that, that the bird and the tree has become one. No. It appears like that. Because both of them are the same color, it appears that the bird has..., there is no more existence of the bird. But that is not a fact. The bird is... Similarly, we are individual spirit soul. The quality being one, say, greenness, when one merges into the Brahman effulgence, the living entity does not lose his identity. And because he does not lose the identity, and because the living entity, by nature, is joyful, he cannot stay in the impersonal Brahman effulgence for many days. Because he has to seek out joyfulness. That joyfulness means varieties.