[i4i]

Nassim Taleb's The Black Swan. At 17 I thought there was nothing that couldn't be achieved by shear will and concentrated effort. The Black Swan introduced me to the notion of Mediocristan and Extremistan, two very different domains with entirely different sets of risk. I don't think I'd have done anything differently, but had I read it earlier, I'd probably not have beat myself up so much when things didn't go well.