I was wondering the other day why we have measures (or bars, as some call them) in music, so I did some online research and the general consensus is: no reason, really. Bars/measures weren't even used until like the 17th century, and most of the articles I read said they're in there to keep the music from running together, and to make it easier for musicians to follow the music and keep the beat. Nobody cites any real sources for that claim, though, so take it with a grain of salt.