During the outbreak of WW2, George Dantzig, a now renowned mathematician, was at university in Paris. He arrived late to his lecture. Contrary to his understanding, he noticed 2 problems on the black board, which he mistook for homework. After the lecture, he set about solving the 2 problems. Within about a week, Dantzig handed his solutions in, apologising that he found them pretty difficult, and the lateness was a reflection of this.
The lecturing pondered over them, realising Dantzig had just solved 2 statistical mathematics problems that were unsolved to that point. The lecturer had written them on the board to give an example of unsolvable problems, but Dantzig missed the start of the lecture, so assumed they were homework.
The lesson: Try not to be late, but if you are late, it might just lead to brilliance