Brilliance or luck ?

I stumbled on that financial forum in which the subject was the possible reasons behind someone's success; was it due to brilliance of luck?

Without getting into the details of the ensuing discussion, my initial response was that, on average, it probably was a mixture of both.

But I added that the catalyst of success when both brilliance and luck were equally involved, was a strong dose of common-sense along with a good sense of timing.

At least this reflect my own experience. What's yours?