On the Move: A Life by Oliver Sacks:
When I got my scholarship to Oxford, I faced a choice: Should I stick to zoology or become a pre-med student and do anatomy, biochemistry, and physiology? It was especially the physiology of the senses that fascinated me—how did we see color, depth, movement? How did we recognize anything? How did we make sense of the world, visually? I had developed these interests from an early age through having visual migraines, for besides the brilliant zigzags which heralded an attack, I might, during a migraine aura, lose the sense of color or depth or movement or even the ability to recognize anything. My vision could be unmade, deconstructed, frighteningly but fascinatingly, in front of me, and then be remade, reconstructed, all in the space of a few minutes.