Civilized men laugh," said Conan. "But not one can tell me how Zogar Sag can call pythons and tigers and leopards out of the wilderness and make them do his bidding. They would say it is a lie, if they dared. That's the way with civilized men. When they can't explain something by their half-baked science, they refuse to believe it.> - Beyond the Black River
This potion clears the knowledge of civilization, wiping away learned skills until the imbiber is left with nothing more than a vast potential for learning. They are then free to sculpt their mind in whichever direction they wish.