“Every living entity within this material world is subject to four deficiencies: he commits mistakes, he accepts one thing for another, he cheats, and he has imperfect senses. The Vedas, however, are not written by any living creature within this material world. Therefore they are said to be apaurusheya. No one can trace out the history of the Vedas.” (Shrila Prabhupada, Shrimad Bhagavatam, 4.2.31 Purport)