The full knowledge is brahmeti bhagavān iti, brahmeti paramātmeti bhagavān iti (SB 1.2.11). The three things one must know. That is full knowledge. But if you understand partially, either Brahman or Paramātmā . . . but if you understand Bhagavān . . . yasmin vijñāte sarvam idaṁ vijñātaṁ bhavati (Muṇḍaka Upaniṣad 1.3). This is Vedic injunction. If you understand Kṛṣṇa, the Supreme Personality of Godhead, then you understand Brahman and Paramātmā. But if you simply understand Brahman or Paramātmā, you do not understand Kṛṣṇa. Therefore it is said, aviśuddha-buddhayaḥ, intelligence is not yet pure. Ye 'nye 'ravindākṣa vimukta-māninas tvayy asta-bhāvād aviśuddha-buddhayaḥ, āruhya kṛcchreṇa paraṁ padaṁ tataḥ (SB 10.2.32). They, after undergoing severe penances and austerities, they approach the Brahman effulgence, param . . . patanty adhaḥ: again falls down. The same example: You may go very high. Just like nowadays, the attempt is being made, they are going to the moon planet or Venus planet. We do not know whether they are going or not, but we hear from the advertisement. So because they do not get any shelter, they come back. Āruhya kṛcchreṇa paraṁ padaṁ tataḥ patanty adhaḥ anādṛta-yuṣmad-aṅghrayaḥ (SB 10.2.32). Because they do not get any shelter, the shelter of lotus feet of Kṛṣṇa, from this impersonal conception of philosophy, they again come to this material world. Therefore you'll find there are so many big, big svāmīs, first of all they give up this world. Brahma satyaṁ jagan mithyā: "This world is mithyā. Let us take to Brahman. Let us become Brahman." But after keeping in . . . some days in so-called Brahman, they again come back to open hospital, school. Because there they could not get anything; therefore something must be done, profession. So open hospital and raise fund. That's all.
So unless you get shelter on the lotus feet of Kṛṣṇa, you'll be attracted by these material activities. But when you are attracted by the lotus feet of Kṛṣṇa, then vīta-rāga-bhaya-śoka . . . then, as we . . . vīta-rāga-bhaya-krodhā man-mayā mām upāśritāḥ (BG 4.10). Mām upāśritāḥ. When you take shelter at the lotus feet of Kṛṣṇa, then you become vīta-rāga-bhaya-krodhāḥ (BG 2.56). Otherwise, you'll be attacked by . . . attracted by this material world. So therefore, artificial śūnyavāda philosophy, it may be, for the time being, necessity, śūnyavāda . . . just like Lord Buddha preached his philosophy, śūnyavāda philosophy, nirvāṇa philosophy, because it was needed at that time. It is not permanent philosophy. Any philosophy except Kṛṣṇa philosophy . . . nothing is permanent. They are temporary. They have got temporary use. The real use is Kṛṣṇa philosophy. Real use, Kṛṣṇa philosophy. Sarva-dharmān parityajya mām ekam . . . (BG 18.66). So when there was . . . people may question that, "Lord Buddha is accepted as an incarnation of Lord Kṛṣṇa," keśava dhṛta-buddha-śarīra jaya jagadīśa hare. "Then why he preached atheistic philosophy?" He preached, "There is no God." Śūnyavāda. But there was necessity at that time.
Why? That is explained by Jayadeva Gosvāmī:
- nindasi yajña-vidher ahaha śruti-jātaṁ
- sadaya-hṛdaya darśita-paśu-ghātam
- keśava dhṛta-buddha-śarīra jaya jagadīśa hare
At that time, people were killing animals like anything in the name of yajña. In the Vedas there are prescriptions that in the yajña a paśu can be . . . an animal can be slaughtered. In some yajña, not all. Tāmasika-yajña. Anyway, Vedic injunction is there. So when Lord Buddha started this nonviolence, ahiṁsā paramo dharmaḥ, the Vedic scholars approached him that, "How you can prescribe this ahiṁsā? There is already sanction in the Vedas, paśavo vadhāya sṛṣṭāḥ . . . how you can stop it?" So Lord Buddha said: "I don't care for your Vedas." Therefore he is considered as atheist. Anyone who doesn't care for Vedas, they are technically called as atheist. Veda nā māniyā bauddha haila nāstika. Nāstika means atheist.
Anyway . . . then Śaṅkarācārya came. Śaṅkarācārya wanted . . . because by the propagation of Lord Buddha, whole India became Buddhist. And Śaṅkarācārya wanted to establish Vedas again. So they were temporary necessities, for certain reason. Because people were addicted so much in violence, in killing the animals, therefore Buddha philosophy was needed. Again, this Buddha philosophy was driven out. The Śaṅkara, impersonal, philosophy was established. But again, the ācāryas, Rāmānujācārya, Madhvācārya and other Vaiṣṇava ācāryas, at last, Caitanya Mahāprabhu, they established that brahma satyam means brahmeti paramātmeti bhagavān iti śabdyate (SB 1.2.11). Both, three, Absolute Truth.
So these are the philosophical development. So Kṛṣṇa is summarizing this philosophical development here in this one line, that mama vartmānuvartante manuṣyāḥ pārtha sarvaśaḥ. Either you follow Buddha philosophy or Śaṅkara philosophy or Vaiṣṇava philosophy, the ultimate goal is Kṛṣṇa. Mattaḥ parataraṁ nānyat kiñcid asti dhanañjaya (BG 7.7). So you have to approach Kṛṣṇa through these different types of philosophy. They are partial realization. Just like Brahman realization means eternity realization, Paramātmā realization means eternity and knowledge, and Bhagavān realization means eternity, knowledge and blissfulness. Sac-cid-ānanda. Īśvaraḥ paramaḥ kṛṣṇaḥ sac-cid-ānanda-vigrahaḥ (Bs. 5.1). If you realize Kṛṣṇa, then you realize simultaneously . . . yasmin vijñāte sarvam idaṁ vijñātaṁ bhavati. You realize Brahman, you realize Paramātmā and you realize Bhagavān. That is our duty.