A world at once familiar and unimaginably strange exists all around us�and within us. It is the world of consciousness, a protean mental landscape that each of us knows intimately in bits and pieces yet understands in its totality scarcely at all. Tied to the body and the brain, consciousness is nonetheless beyond our ability to measure or quantify. Despite the attempts of scientists and mystics, poets and dreamers, crackpots and geniuses, to map its contours and explain its secret workings, the mind remains mysterious. And the more we learn about it, the more mysterious it becomes.