Prabhupāda: Yogaḥ proktaḥ purātanaḥ. Purātanaḥ, not something new. This is nonsense. There cannot be anything new. Everything established. Science means . . . scientific knowledge means it is not something new. Just like the sun rises from the eastern horizon. So millions of years ago, the sun used to rise from the eastern horizon - still it is going on. Not that because time has changed, the sun is rising from the western side or northern side. No. Knowledge means . . . That is Vedic knowledge: established knowledge. It cannot be changed in any circumstances. That is Vedic knowledge. What was millions of years ago fact, it is fact now. So, tad-vijñānārthaṁ sa gurum evābhigacchet (MU 1.2.12). So in order to know that factual knowledge, one has to approach the bona fide spiritual master.
We have several times explained this, who is bona fide spiritual master, confirmed by Caitanya Mahāprabhu. Caitanya Mahāprabhu said that āmāra ājñāya guru hañā, "You become a guru on My instruction." So those who are affiliated with Caitanya Mahāprabhu's instruction, he is guru. Not anyone else. Āmāra ājñāya guru hañā tāra' ei deśa (CC Madhya 7.128). Then one may argue that if Caitanya Mahāprabhu is ordering, then anyone can order? No, Caitanya Mahāprabhu is not ordering something new. Caitanya Mahāprabhu says that "Under My instruction you become guru." But the instruction is Kṛṣṇa's, the same instruction, yāre dekha tāre kaha kṛṣṇa-upadeśa (CC Madhya 7.128). Caitanya Mahāprabhu also does not deviate from Kṛṣṇa's upadeśa, what to speak of others. And those rascals who are deviating from the instruction of Kṛṣṇa, how he can become guru? They are interpreting in a different way, how they can become guru? That is not guru. We should simply remember this fact: whether this person is speaking the same thing as Kṛṣṇa says, as Caitanya Mahāprabhu says, as Rāmānujācārya says, even Śaṅkarācārya.
He, superficially he might have said something which is not understandable, but he also followed the same thing: bhaja govindaṁ bhaja govindaṁ bhaja govindaṁ mūḍha. But due to unfavorable time, he had to say about impersonal feature. But ultimately he said, bhaja govindaṁ bhaja govindam, bhaja govindaṁ mūḍha mate: "You rascal, you just worship Govindam." And this jugglery of words, grammatical jugglery, will not help you at the time of death. Nahi nahi rakṣati dukṛn-karaṇe. If you misinterpret, that "With this grammatical addition or grammatical alteration this meaning can be derived," no. That is malinterpretation. Real understanding is bhaja govindam. Govindam ādi-puruṣaṁ tam ahaṁ bhajāmi. Lord Brahmā, he also says, govindam ādi-puruṣaṁ tam ahaṁ bhajāmi. And Śrīpāda Śaṅkarācārya, he is incarnation of Śaṅkara, he also saying, govindam, bhaja govindam bhaja govindam bhaja govindam. And we are following the same thing, so that is guru-paramparā, that is real knowledge. So don't approach a cheater, but actually approach a teacher, not a cheater. Then bhakti-yoga will be . . . That teacher is guru, and he is representative of Kṛṣṇa. He does not say anything else.