In 1960, my Mum (transatlantic translation - Mom) was in a club in the centre of her home town of Liverpool. The space was hot smoky and loud. On the other side of the room was a serious looking man with glasses and a long delicate nose. She smiled at him, he smiled back. Then, just as he was about to approach her, he was distracted by a blonde girl with white stilettoes and beehive hair. The young man in question was John Lennon. This little tale illustrates how the slightest beat of the butterflies wing carries away a moment of chance only to land it on some other girl's unsuspecting shoulder.
It also quite neatly explains why I do not own an apartment overlooking Central Park.