The Will to Power · Friedrich Wilhelm Nietzsche
487.
Should not all philosophy ultimately disclose the first principles on which the reasoning processes depend?--that is to say, our _belief_ in the "ego" as a substance, as the only reality according to which, alone, we are able to ascribe reality to things? The oldest realism at length comes to light, simultaneously with man's recognition of the fact that his whole religious history is no more than a history of soul-superstitions. _Here there is a barrier;_ our very thinking, itself, involves that belief (with its distinctions--substance, accident, action, agent, etc.); to abandon it would mean to cease from being able to think. But that a belief, however useful it may be for the preservation of a species, has nothing to do with the truth, may be seen from the fact that we _must_ believe in time, space, and motion, without feeling ourselves compelled to regard them as absolute realities.
Text from Project Gutenberg, public domain in the United States.