True knowledge is learning to serve Krishna in nine different ways through undeviating devotion.Listen — Srila Prabhupada Uvaca
Śrīmad-Bhāgavatam 7.5.22–30 — September 8, 1971, London 710908SB-LONDON [49:21 Minutes] SB-07.05.22–30_710908SB-LONDON Devotee: [introducing recording] London lecture number 15, evening, September 8th, 1971, London temple. [break] Prabhupāda: ...Prahlāda Mahārāja, at the age of five years only, he was a great devotee. Prahlāda Mahārāja is one of the mahājana, great authority of this line, devotional line. [aside:] You can take your seat. To understand God and to understand our relationship with God, it is not to be done by mental speculation. It is not possible.
God is not so cheap thing that one can understand by mental speculation. In the present age people are very much fond of mental speculation. In the śāstra it is said, tarko apratiṣṭhaḥ [Cc. Madhya 17.186]: "Simply by arguing you cannot come to the right conclusion." You may be very good arguer, but another arguer may defeat you by his argument.
So in this way, simply by dry arguments it is not possible to come to the conclusion. Tarko 'pratiṣṭha śrutayo vibhinnāḥ. Scripture. There are different scriptures, so if you simply... Scripture means Vedic, the Vedas.
There are four Vedas and many other also, corollaries. So by studying at home these books, that is also not possible to understand. And nāsau munir yasya mataṁ na bhinnam. And if you follow philosophers, so one philosopher is differing from another philosopher.
Just like our Śyāmasundara has brought one book, Ideas of Philosophers, different philosophers talking differently. So how you can take the conclusion? Even Aristotle, he is talking so many things nonsense. So mental speculators, philosophers, in this way you cannot. Dharmasya tattvaṁ nihitaṁ guhāyām.
Actually, the purport of religion and God is very confidential. Therefore, to understand it, one has to follow the great authorities, mahājano yena gataḥ sa panthāḥ [Cc. Madhya 17.186]. Mahājana.
So that mahājanas, great authorities, are also mentioned, who are mahājanas, authorities. So, svayambhūr nāradaḥ śambhuḥ kumāraḥ kapilo manuḥ prahlādo janako bhīṣmo balir vaiyāsakir vayam [SB 6.3.20] Everything is there in the śāstras. If you simply refer to śāstras for the right source of knowledge, then you get. In the Bhagavad-gītā also it is said, yaḥ śāstra-vidhim utsṛjya.