The Mind’s Eye would have been a disappointment had it looked no further for clinical material. But there’s a redeeming fifth case: Oliver Sacks. And when the author steps into the clinical spotlight the book comes to life. His well-documented absent-mindedness, ]what is variously called my “shyness”, my “reclusiveness”, my “social ineptitude”, my “eccentricity”, even my “Asperger’s syndrome”’, can, he thinks, be put down to lifelong face blindness. A rare consequence of brain injury, it is now understood to be quite common in the general population, varying in severity from habitual misrecognition of acquaintances to not recognising one’s own children. Sacks’s problem seems to fit at the more severe end of the spectrum, among those who are discombobulated even by their own reflection. On one occasion, he finds himself grooming his beard in a restaurant window only to realise that ‘what I had taken to be my reflection… was in fact a grey-bearded man on the other side of the window, who must have been wondering why I was preening myself in front of him’.