Sunshine is over-rated in sport and stillness is overestimated. In perfect weather is born the most fluent skill, but it is on imperfect days that ruggedness is revealed. In the freezing night of a 1,500m race, the sweltering cricket day of sweat and vomit, the rainy afternoon which tests the footballer's balance, we get to see character.
And so the gusting wind that led her to errors and screams and racket thumps in the US Open final was in a curious way a blessing. Because it led to survival tennis. Dig-deep tennis. C'mon-dammit-fight tennis. Serena tennis. Nature's interference just brought out the best part of her nature.
Serena's serve reminds me of Hessie Donahue, a 1892 matron who knocked out boxing champion John L. Sullivan while sparring with him. Her stroke armoury is so versatile that Victoria Azarenka said: "Sometimes she really goes for it; sometimes she finds great depth; sometimes she finds good angles."
But it is Serena's toughness, a quality easier to recognise in sport than precisely define, which is her primary trait. It is, in a sense, a defiance, which is simply, almost childishly, expressed in a match-book entry reprinted in her 2009 autobiography:
"Tell me 'No' and I'll show U I can. Tell me 'No' because I can! Tell me 'No'. Go ahead, tell me. Just tell me I can't win. Just tell me it's out of reach. Come on. I'll prove you wrong. Just tell me 'No' and watch what happens."
In another book, the gripping The Sports Gene - which I have just started - author David Epstein travels through a measured world of reflex, speed, practice, all the while splicing apart and examining the working parts of athletes. But this thing Serena has, this "irrational killer instinct" as she calls it in her book, has an unquantifiable mystery to it.
Azarenka said there's "one word" for it: champion. But Serena can't readily explain what makes champions. Can't tell you why she made her choices yesterday and won even after "not playing smart"; can't say why after twice failing to close the match she did not fade; can't explain why she looked at this pushy Belarusian, who at 24 is like a younger, fearless version of her and still believed she could win.
Athletes anyway are careful of defining their own greatness for it can smell of conceit. Roger Federer once said, "I always knew I had something special, but I didn't know it was that crazy" and his honesty did him no good. So, perhaps, it is best that Azarenka speaks for who Serena is.