Comment by waterhouse

A guy I know—who basically spends his time around high-IQ kids, seems to be on speaking terms with several Fields Medalists, and has closely studied the lives of lots of great scientists and mathematicians—says that great achievement comes from three ingredients: (a) mental horsepower (roughly measured by IQ); (b) taste, an aesthetic sense that helps one decide to work on the right things or investigate the right hypotheses; and (c) obsessiveness, such that when you encounter a project that truly is worth working on, you're likely to spend enormous amounts of time working on it. (The big-5 trait Conscientiousness may be one way of implementing (c).)