From the New Yorker, “Creation Myth: Xerox PARC, Apple, and the truth about innovation,” by Malcolm Gladwell:

The difference between Bach and his forgotten peers isn’t necessarily that he had a better ratio of hits to misses. The difference is that the mediocre might have a dozen ideas, while Bach, in his lifetime, created more than a thousand full-fledged musical compositions. A genius is a genius, Simonton maintains, because he can put together such a staggering number of insights, ideas, theories, random observations, and unexpected connections that he almost inevitably ends up with something great. “Quality,” Simonton writes, is “a probabilistic function of quantity.”

Simonton’s point is that there is nothing neat and efficient about creativity. “The more successes there are,” he says, “the more failures there are as well”—meaning that the person who had far more ideas than the rest of us will have far more bad ideas than the rest of us, too. This is why managing the creative process is so difficult.