So what happens when you work neuroscience? When you read of the man who mistook his wife for a hat? Or the artist who lost all sense of colour and could only eat food that was black and white because everything looked grey? Or the woman who forgot how her body moved in space? Those who have followed the works of Oliver Sacks will recognise the case studies from The Man Who Mistook His Wife for a Hat and An Anthropologist from Mars. They will remember the fear they felt at all the things that can go wrong. One moment of carelessness, one stray automobile and your life is changed irrevocably. Once your brain changes, you change. How you change depends on which parts of the brain have been affected. Nothing else constitutes you or even your notion of you. Neuroscience is making us aware of our fragility and the even greater and more frightening fragility of the reality we create for ourselves through the perceptions the brain moderates and sorts for us.