How did the superstition that broken mirrors cause bad luck start and why does it still exist?

  Every human culture has superstitions. In some Asian societies, people believe that sweeping a floor after sunset brings bad luck and that it’s a curse to leave chopsticks standing in a bowl of rice. In the U.S., some people panic if they accidentally walk under a ladder or see a black cat cross their path. Also, many tall buildings don’t label their 13th floors as such because of that number’s association with bad luck.