You are the only thing in the universe you know from the inside. Nobody can explain how that is possible.

Science can trace a photon from this page to your retina, through the optic nerve, into the visual cortex, and out again as the movement of your eye. What it cannot do is explain why any of that is like something. Why there is a view from in here at all.

This is the hard problem of consciousness, and it is the last great gap in our picture of the world. We have mapped the genome, photographed a black hole and measured the mass of the Higgs boson. Meanwhile the single most obvious fact about your existence sits outside the reach of our best physics.

The Last Mystery is a clear-eyed tour of that gap, written for anyone who has a mind and would like to understand what one is. No background in neuroscience or philosophy required.