 And it started in medieval times when in competitions, often men who were the best shot became widely popular when archery was very popular for fighting and exhibition sports. So never to be caught short, the best archers would add another string to their bow. They'd attach a second string at the top of the bow that was wound around the handle. If the first string snapped or was damaged, the archer had a backup string to get him out of trouble. And that's also how the expression second string came about.