Bhagavad Gita AS IT IS: The Vedic histories, the Puranas and Mahabharata, relate human histories which extend millions and billions of years into the past.For example, from these literatures we are given the histories of Krsna's appearances and disappearances millions and billions of years ago.In the Fourth Chapter of the Bhagavad-gita Krsna tells Arjuna that both He and Arjuna had had many births before and that He (Krsna) could remember all of them and that Arjuna could not. This illustrates the difference between the knowledge of Krsna and that of Arjuna. Arjuna might have been a very great warrior, a well-cultured member of the Kuru dynasty, but after all, he was an ordinary human being, whereas Krsna, the Supreme Personality of Godhead, is the possessor of unlimited knowledge. Because He possesses unlimited knowledge, Krsna has a memory that is boundless.Krsna's knowledge is so perfect that He remembers all the incidents of His appearances some millions and billions of years in the past, but Arjuna's memory and knowledge are limited by time and space, for he is an ordinary human being. In the Fourth Chapter Krsna states that He can remember instructing the lessons of the Bhagavad-gita some millions of years ago to the sun-god, Vivasvan.