Prabhupāda: Means calculation. It is going on, regulated way. Just like everyone knows that this month is February. In the month of June the summer will begin. Everyone knows. It is not conclusion; it is experience. There is no need of calculating. So one who has got better experience, he can say like that. Calculation and experience. Just like if somebody says, "Two plus two plus two plus two," somebody says immediately, "Six." And another calculates, "Two plus two plus..., six." So experience and calculation. Lacks experience, he calculates. One who has better experience, he doesn't calculate. One who knows past, present, and future, he doesn't require to make calculation. He knows everything. So God knows past, present, and future, and others who are favored by God, he also knows by the grace of God. Because he hears from God. God knows past, present, and future. Then he simply reproduces God's words, that's all. He doesn't require to calculate. Just like in the Bhagavad-gītā it is said, sahasra-yuga-paryantam ahar yad brahmaṇo viduḥ (BG 8.17). The Kṛṣṇa says. Now, we can say what is the age of Brahmā by Kṛṣṇa's words. I don't require to be a very expert astrologer or astronomer. I hear from Kṛṣṇa, and I reproduce. Just like child. Father said, "This is this;" I say, "This is this." That's all. The child is not perfect, but when he says, "Father said this is this," that is perfect. Therefore our process of gathering knowledge from the father—we don't calculate or don't concoct or put theories, no. We don't do that. This is called śruti, śruti-pramāṇa, evidence from śruti.