So in the śāstra we find, kṛte yad dhyāyato viṣṇuḥ (SB 12.3.52). Real yoga system, I've already explained, that yoga indriya saṁyamaḥ, or by meditation to see the Supreme Lord always within the heart. Dhyānāvasthita-tad-gatena manasā paśyanti yaṁ yoginaḥ (SB 12.13.1). In trance, you'll find yogi picture, their trance, they are in meditation, completely silent, stop breathing and seeing the Supreme Personality of Godhead, Viṣṇu, within the heart. This is actual yoga system. But it was possible to be executed in the Satya-yuga. Satya-yuga means when people used to live for one hundred thousands of years. That was possible. Just like Vālmīki Muni. He executed yoga system for sixty thousand years. Because he was to live for one hundred thousands of years, so it was not very difficult to engage oneself for sixty thousands of years. But that is not possible in this age. Therefore śāstra says,
- kṛte yad dhyāyato viṣṇuṁ
- tretāyāṁ yajato makhaiḥ
- dvāpare paricaryāyāṁ
- kalau tad dhari-kīrtanāt
- (SB 12.3.52)
Kalau, in this Kali-yuga, when people are very, very fallen... Mandāḥ sumanda-matayo manda-bhāgyā hy upadrutāḥ (SB 1.1.10). They are very unfortunate also, and manda-bhāgyā, and although unfortunate, they are disturbed by so many external factors. So it is very difficult to execute yoga system or yajña system, sacrifice. It is very costly affair. Or even arcana, temple worship, it is also very difficult, because people are not very much interested even, worshiping the Deity in the temple. In India there are thousands and thousands of temples, temple or mosque or church, at the same time, for offering prayers, obeisances to the Lord. People are losing interest in that arcana-mārga. There are many temples I have seen, there is no caretaker. People are losing interest. Many temples. They are open; a dog is living within the temple and passing stool. I have seen it.
So people are gradually losing interest in temple worship even, what to speak of yoga or offering sacrifices. Everything is now finished. Therefore kalau tad dhari-kīrtanāt. This is prescribed in the śāstra. That system was introduced by Caitanya Mahāprabhu. Because other system will not be successful in this age. May be successful in one or two cases, but not for the general mass of people. Therefore śāstra recommends... There are different incarnation of God, but one incarnation is there, it is mentioned in the Śrīmad-Bhāgavatam and other places also, in Upaniṣad and Mahābhārata. These are approved Vedic scriptures. So the Vedic knowledge is summarized in the Vedānta system, Brahma-sūtra, everything done by Vyāsadeva. And in order to protect the sanctity of Vedānta... Because there are so many foolish persons, they are distorting the purpose of Vedānta-sūtra; therefore Vyāsadeva, under the instruction of his spiritual master Nārada, he personally wrote a commentary on the Vedānta-sūtra. This is Śrīmad-Bhāgavatam. So Śrī Caitanya Mahāprabhu introduced these two things—saṅkīrtana and Śrīmad-Bhāgavatam. And Śrīmad-Bhāgavatam means the expansion of Bhagavad-gītā. Just like in the Bhagavad-gītā you'll find, at the last stage, Kṛṣṇa says, sarva-dharmān parityajya mām ekaṁ śaraṇaṁ vraja (BG 18.66). And Śrīmad-Bhāgavatam also begins from that point. Śrīmad-Bhāgavatam gives introduction, dharmaḥ projjhita-kaitavo 'tra (SB 1.1.2). All cheating type of religious system kicked out, projjhita. Projjhita means just like you sweep over the floor, and all the dust, you throw it away. That is called projjhita. Prakṛṣṭa-rūpeṇa ujjhita.
So this system, one system, to accept the real principles of religion. That is, Kṛṣṇa also explained. It is explained by Kṛṣṇa, that Kṛṣṇa came, appeared. Why? What is the purpose of Kṛṣṇa's appearing? Sometimes they argue, atheist class of men, that God cannot come. Why God cannot come? God is your father's servant, that He cannot come? You are ordering? If He cannot come, how He is God? God can do everything. Why you say that God cannot come? He is not under your rules and regulations. Then He is not God. God can come. God says, "Yes, I come!"