A quote, from "Benjamin Button"

Sometimes we're on a collision course, and we just don't know it. Whether it's by accident or by design, there's not a thing we can do about it. A woman in Paris was on her way to go shopping, but she had forgotten her coat - went back to get it. When she had gotten her coat, the phone had rung, so she'd stopped to answer it; talked for a couple of minutes. While the woman was on the phone, Daisy was rehearsing for a performance at the Paris Opera House. And while she was rehearsing, the woman, off the phone now, had gone outside to get a taxi. Now a taxi driver had dropped off a fare earlier and had stopped to get a cup of coffee. And all the while, Daisy was rehearsing. And this cab driver, who dropped off the earlier fare; who'd stopped to get the cup of coffee, had picked up the lady who was going shopping, and had missed getting an earlier cab. The taxi had to stop for a man crossing the street, who had left for work five minutes later than he normally did, because he forgot to set off his alarm. While that man, late for work, was crossing the street, Daisy had finished rehearsing, and was taking a shower. And while Daisy was showering, the taxi was waiting outside a boutique for the woman to pick up a package, which hadn't been wrapped yet, because the girl who was supposed to wrap it had broken up with her boyfriend the night before, and forgot. When the package was wrapped, the woman, who was back in the cab, was blocked by a delivery truck, all the while Daisy was getting dressed. The delivery truck pulled away and the taxi was able to move, while Daisy, the last to be dressed, waited for one of her friends, who had broken a shoelace. While the taxi was stopped, waiting for a traffic light, Daisy and her friend came out the back of the theater...

And if only one thing had happened differently: if that shoelace hadn't broken; or that delivery truck had moved moments earlier; or that package had been wrapped and ready, because the girl hadn't broken up with her boyfriend; or that man had set his alarm and got up five minutes earlier; or that taxi driver hadn't stopped for a cup of coffee; or that woman had remembered her coat, and got into an earlier cab, Daisy and her friend would've crossed the street, and the taxi would've driven by.
But life being what it is - a series of intersecting lives and incidents, out of anyone's control - that taxi did not go by, and that driver was momentarily distracted, and that taxi hit Daisy, and her leg was crushed.