Until 50 years ago, many believed it was impossible to understand the secret of life. Then, the two scientists James Watson and Francis Crick discovered the structure of DNA, fundamentally changing the way we see ourselves in the natural order of things. Today, we face a similar challenge when we seek to determine the material basis of consciousness. Consciousness is one of the last great unsolved mysteries of science and certainly the greatest in biology. We can taste the salty flavor of potato chips, perceive the unmistakable smell of dogs after they've been in the rain, and experience the unique feeling of climbing many meters above solid ground, hanging only by our fingertips on a rock face. How can these impressions arise from neurons and the associated synapses and molecules?.