What you do not know exactly—simply theoretically you put some theories and speculate—that is not knowledge. But our process, we are getting knowledge from the perfect personality. That is Vedic system. You acquire knowledge from a person who is perfect in knowledge. Perfect in knowledge and imperfect in knowledge . . . so long we are imperfect, we cannot give perfect knowledge. Therefore we must find out knowledge from the perfect person. That is Vedic injunction. Tad-vijñānārthaṁ sa gurum eva abhigacchet (MU 1.2.12). Guru, guru means one who has got perfect knowledge. One who hasn't got perfect knowledge, he cannot become guru. How he can? Guru means heavy. So if I am light and I take knowledge from another light person, then what is the use of such knowledge?
So therefore the Vedic injunction is tad-vijñānārthaṁ sa gurum eva abhigacchet (MU 1.2.12). Abhigacchet, "must." Gacchet. This form of verb, vidhi-ling, is used when there is the meaning "must." Abhigacchet. So it is not optional, that "I may go or I may not go." No. You must go. That is Vedic injunction. So here is the perfect teacher, Kṛṣṇa, real jagad-guru. Kṛṣṇa, the Supreme Personality of Godhead, it appears in due course of time. There is a time when Kṛṣṇa appears. Everything is there in the calculation of the śāstras. Just like we have got a fixed time for the sunrise. Everyone knows that in the morning at 6:30 there will be sunrise. That is certain. Similarly, in the śāstras there is description when Kṛṣṇa comes down, descends, in this universe. In one day of Brahmā at the end of Dvāpara-yuga . . . Brahmā's days are described in the Bhagavad-gītā, sahasra-yuga-paryantam ahar yad brahmaṇo viduḥ (BG 8.17). Forty-three lakhs of years multiplied by one thousand becomes one day of Brahmā. So forty-three lakhs thousand times, add another forty-three lakhs thousand times—this is the period after which Kṛṣṇa comes.
So why does He comes, that is also described. Paritrāṇāya sādhūnāṁ vināśāya ca duṣkṛtām, yuge yuge sambhavāmi (BG 4.8). So the Supreme Personality of Godhead, Kṛṣṇa, descends to give us knowledge like Bhagavad-gītā, personally speaking, so that even after disappearance of Kṛṣṇa, you can take advantage of Bhagavad-gītā and, as Arjuna is asking personally, so similarly, all your questions, not only religious . . . of course, when there is something talks about God, it is taken as religious. So religious, the meaning of religion in the English dictionary is different from what we mean by religion, that in the dictionary it is said: "Religion is a kind of faith." Faith may be wrong or right, but religion cannot be wrong or right. Religion must be correct. That is the meaning of religion. The example is that the sugar is sweet. It is not the question of wrong or right. Sugar must be always sweet. You cannot change it. That is religion. Chili is hot. That is correct. Chili cannot be sweet, and sugar cannot be hot.