When Einstein was a very young man, he worked for a grocer.
One day, the grocer assigned him to arrange the meat and the vegetables in the display case.
Later, when he checked on young Albert's work, he was less than satisfied. He told Einstein in very explicit terms exactly how he wanted things arranged, even giving him a note so he wouldn't forget the instructions.
Basically, he wanted every one of his finest cuts of meat to be arranged in the middle of a square display of celery.
Years later, Albert was at college, and discovered a note in his jacket pocket.
E = mc2
He never could remember exactly what it was about.