Critics said he won many battles simply because of luck; Napoleon responded, "Give me lucky generals," aware that "luck" comes to leaders who recognize opportunity, and seize it.
Bizarre - the last link I was on was a random ESPN quiz with UVa star Joe Harris in which that quote was one of the questions. (I realize this is a pretty meaningless and useless comment, but seeing this quote 2 times in less than 10 seconds was too much not to mention).
Is it bizarre? Given the number of people on HN, the number of things you're likely to read -- it seems inevitable that "bizarre" coincidences will certainly happen.
I'm unable to find a definitive reference, but Gary Player (golfing legend) is also attributed with the quote: "The harder I practice, the luckier I get." Perhaps that's why it was on ESPN.
Pretty sure George Simmons has this quote of Player's on one of the chapter pages in his "Precalculus Mathematics in a Nutshell" book.
The upshot is that its origin is unknown, but goes back at least to a Walter Winchell column from 1949. Gary Player used it and became associated with it. The attribution to Jefferson is nonsense, of course.
It was just because Thomas Jefferson said it and Joe Harris goes to the University he founded, it's just bizarre that I saw it 2 times in less than 10 seconds.
-- Thomas Jefferson (apocryphal; see [0])
[0]: http://www.monticello.org/site/research-and-collections/i-am...