If he makes research work to find out his father, he'll never find out his father. But if he asks his mother, "Who is my father?" and the mother says, "He is your father," that is perfect. Therefore knowledge, knowledge of God, who is beyond your sense perception, how can you know? Therefore you have to know from God Himself or His representative.
So here Kṛṣṇa, the Supreme Personality of Godhead, is speaking, and that is the final authority. He says to Arjuna as follows. He says, aśocyān anvaśocas tvaṁ prajñā-vādāṁś ca bhāṣase: (BG 2.11) "My dear Arjuna, you are talking like very learned scholar, but you are lamenting on a subject matter which you should not do." Gatāsūn agatāsūṁś ca nānuśocanti paṇḍitāḥ. Gatāsūn means this body. When it is dead or when it is alive, bodily conception of life is foolishness. So no learned man takes serious consideration of the body.