The emerging picture from studies of high achievers in many fields is that ten thousand hours of practice are required to achieve the level of mastery associated with being a world-class expert–in anything. In study after study–of composers, basketball players, fiction writers, ice skaters, concert pianists, chess players, master criminals, and what have you–this number comes up again and again. Ten thousand hours is equivalent to roughly three hours a day, or twenty hours a week, of practice over ten years. Of course, this doesn’t address why some people don’t seem to get anywhere when they practice, and why some people get more out of their practice sessions than others. But no one has yet found a case in which true world-class expertise was accomplished in less time. It seems that it takes the brain this long to assimilate all that it needs to know to achieve true mastery.