Kalpa means the duration of one creation. This material creation, bhūtvā bhūtvā pralīyate (BG 8.19), it is created at a certain interval, and it stays for some time, again it is annihilated. So again, at the time of creation, if somebody is not available, then the Supreme Lord Kṛṣṇa, He becomes Brahmā Himself.
- yasyāṅghri-paṅkaja-rajo 'khila-loka-pālair
- mauly-uttamair dhṛtam upāsita-tīrtha-tīrtham
- brahmā bhavo 'ham api yasya kalāḥ kalāyāḥ
- śrīś codavahema ciram asya nṛpāsanaṁ kva
- (CC Madhya 20.306)
So:
- nijāṁśa-kalāya kṛṣṇa tamo-guṇa aṅgīkari'
- saṁhārārthe māyā-saṅge rudra-rūpa dhari
- (CC Madhya 20.307)
Similarly, sometimes, when Śiva is not available . . . Śiva is available. Nijāṁśa-kalāya kṛṣṇa tamo-guṇa aṅgīkari'. Now Kṛṣṇa, the Lord Himself, when He accepts the management of these modes of ignorance, He is called Śiva. So Śiva, Śiva is God, but because he is in the department of ignorance, therefore his name is Śiva. He makes śiva. Śiva, another meaning of śiva is "auspicious." These inauspicious persons who are in ignorance, for them, Śiva worship, worship of Lord Śiva, is recommended so that gradually they come to the modes of passion and goodness, and then they are liberated.
So nijāṁśa-kalāya kṛṣṇa tamo-guṇa aṅgīkari', saṁhārārthe. But his business is destruction. When there is some destruction in this material world, you should know that is the action of Śiva. Perhaps you have seen one statue that is very popular, sold in antique shops—Naṭarāja, dancing and fire, all round there is fire. When Śiva begins to dance, his dance is very serious. As you dance, kṛṣṇa-kīrtana, so similarly Śiva also dances for annihilation. There is fire. By his dancing, there will be fire. Saṁhārārthe māyā-saṅge rudra-rūpa dhari. Māyā-saṅge. He has got connection with this material energy, and he is meant for destruction. Material energy is under the, I mean to say, control of this Śiva-rūpa of Kṛṣṇa. Therefore he is called father. He is called father, and the material energy is called mother. Father and mother, Durgā.
- māyā-saṅga-vikāri rudra—bhinnābhinna rūpa
- jīva-tattva haya, nahe kṛṣṇera 'svarūpa'
- (CC Madhya 20.308)
And because he has connection with this illusory energy, therefore he is not exactly God. God has nothing to do with this material energy, illusory energy. He is never illusioned. But Śiva, Lord Śiva, he has connection with Durgā, the material energy. Therefore his position is between the living entity and Kṛṣṇa. Now Lord Caitanya is quoting one verse from Brahma-saṁhitā about the real position of Śiva:
- dugdha yena amla-yoge dadhi-rūpa dhare
- dugdhāntara vastu nahe, dugdha haite nāre
- (CC Madhya 20.309)
A very nice example. Just like if you mix up with milk something sour and it turns into yogurt or curd, similarly, the difference between Śiva and Lord Kṛṣṇa is like that. He is Kṛṣṇa, but because he is mixed up with this material energy, therefore he is something like that yogurt.
So yogurt, the constitutional position of yogurt is nothing but milk, but it cannot become milk again. Once turned into yogurt, there is no possibility of turning into milk. Neither you can derive the benefit of milk from yogurt. Yogurt is used for some purpose, milk is used for some other purpose.
Similarly, those who are worshipers of Śiva, they cannot derive the same benefit as persons who are in Kṛṣṇa consciousness. Just like you cannot derive the same benefit by drinking . . . by taking yogurt. If you require milk, if I supply you yogurt, it will give another, I mean to say, disturbance. Similarly, the distinction is given here, and He is quoting from Brahma-saṁhitā, most authoritative literature in this connection.
- kṣīraṁ yathā dadhi vikāra-viśeṣa-yogāt
- sañjāyate na tu tataḥ pṛthag asti hetoḥ
- (CC Madhya 20.310)
Śiva is not different from Kṛṣṇa, but it is added with this material energy. Therefore Śiva has turned into yogurt.
- yaḥ śambhutām api tathā samupaiti kāryād
- govindam ādi-puruṣaṁ tam ahaṁ bhajāmi
- (CC Madhya 20.310)
But somebody is required for destruction, so that destruction part is taken by Śiva, and he is in charge of this tamo-guṇa.
- 'śiva'—māyā-śakti-saṅgī, tamo-guṇāveśa
- māyātīta, guṇātīta 'viṣṇu'—parameśa
- (CC Madhya 20.311)
So, therefore Viṣṇu and Śiva, the difference is that Viṣṇu is never in touch of this illusory energy, or material energy, but Śiva is in intimate touch with the material energy. That is the difference between Śiva and Viṣṇu.