Each of us lives within the universe - the prison - of his own brain.

Each of us lives within the universe - the prison - of his own brain. Projecting from it are millions of fragile sensory nerve fibers, in groups uniquely adapted to sample the energetic states of the world around us: heat, light, force, and chemical composition. That is all we ever know of it directly all else is logical inference.

Each of us believes himself to live directly within the world that surrounds him, to sense its objects and events precisely, and to live in real and current time. I assert that these are perceptual illusions ... Each of us lives within the universe - the prison of his own brain.