Such is this relativity of all things to their knower that because the world we experience is our mental world, we never see the world as it really is in itself or as a being who was observing it from outside would observe it. The consequence is that we never see the world without unconsciously seeing the world mixed up with the self. The "I" plus something other than the "I" constitute our field of consciousness. We never know the world-in-itself but only the world-in-a-state-of-interaction-with-the-self. We never know the self-in-itself but only the self-in-a-condition-of-interaction-with-the-world. Such are the actual and compulsory conditions of the so-called experience of the world and our so-called experience of the self.
-- Notebooks Category 19: The Reign of Relativity > Chapter 1: The Cosmos of Change > # 72
-- Perspectives > Chapter 19: The Reign of Relativity > # 6