The striking thing about Ericsson's study is that he and his colleagues couldn't find any 'naturals,' musicians who floated effortlessly to the top while practicing a fraction of the time their peers did. Nor could they find any 'grinds,' people who worked harder than everyone else, yet just didn't have what it takes to break the top ranks. Their research suggests that once a musician has enough ability to get into a top music school, the thing that distinguishes one performer from another is how hard he or she works. That's it. And what's more, the people at the very top don't work just harder or even much harder than everyone else. They work much, much harder. The idea that excellence at a complex task requires a critical minimum level of practice surfaces again and again in studies of excellence. In fact, researchers have settled on what they believe is the magic number for true expertise: ten thousand hours.