The smile of Nicola Adams has been one of the trademarks of these joyous Olympics, but you do not win a gold medal - and a shared experience with your life-long idol Muhammad Ali - with mere amiability.
She did it, mostly, with a series of impressively timed left-right combinations that systematically destroyed her formidable, three-time world champion Chinese opponent Ren Cancan.
Afterwards, of course, the smile returned strongly enough to cover a large tract of east London - and well it might have because she had done rather more than make history as the first woman able to hang from her neck the prize won by her inspiration Ali in the Rome Olympics 52 years ago.
Who knows quite how many hurts and patronising put-downs have lurked below the surface of her fight to fulfil the ambition which in victory she declared was "the dream I've wanted all my life"?
What we do know is that even now the woman boxer is - at least beyond the boundaries of the fiercely united British team - not universally approved. Some say such a contender is intruding into a male preserve and that she is neither physically nor psychologically equipped for the job.
Peevish and ungenerous though this thought may be, it is a lot better than the claim that women who fight are merely objects of male sexual titillation. In any event, however you tabulate these complaints, there was only one place to put them after yesterday's performance. It was in the rubbish can reserved for stale prejudice. Perhaps out of deference to the occasion, Adams postponed her routine Ali shuffle until her hand was raised, a formality reflected by the score of 16-7.
The southpaw Ren, who had beaten Adams in their last two meetings, has a style which the great Lennox Lewis briefly contemplated yesterday before declaring it "weird".
However, in the not hugely peopled ranks of women's boxing Ren has developed a formidable reputation for the compiling of points while avoiding much contact with the gloves of opponents. Lewis certainly agreed that she was hard to hit, which was something which coloured his praise for the way Adams picked her moments and exploited them with such sharp force.
Breaking point for Ren came in the second round when Adams had absolute authority and it would have taken a lot more than a gum-shield to have contained the spread of that grin.
"I'm taking this medal back to Leeds because it belongs as much to all those people who've given their support as it does to me," she said.
Certainly one imprint belongs to Ali. "When I was a kid I spent so much time watching him when the old fights were re-run. He delighted me so much with his skill and his personality and the way he affected people. I said: 'I want to be like him'."
Either side of the gender line, ambition can hardly have arrived more weightily but if no one fights like Ali, at least some of his spirit and nature and love of the fight and the show can be reproduced to varying degrees.
She has other ambitions, including one to be a TV actress after work on Coronation Street and Emmerdale.
But there has never been much doubt about the one that rests closest to her heart. Yesterday she found its perfect expression. We do not know how many young girls will now be inspired to go to their local gym and brave all that rough, macho lore that goes on in such places. But we can guess it will be more than ever before because they have just seen Nicola Adams do, triumphantly, that thing which she has always wanted to.
Adams fought the fight of her life yesterday - and she also justified that old decision to go where she was not at first rapturously welcomed. No one could've better represented her country or her sex.
She made boxing history, certainly, but she also delivered a fine one-two on behalf of personal freedom.