<iframe width="580" height="385" src="https://www.youtube.com/embed/KBX0ylUDfXo?autoplay=1" frameborder="0" allowfullscreen></iframe> <br>We're generally keener on performing it than thinking about why we do so. Here's a small attempt to redress the balance. <br><a href="https://www.youtube.com/watch?v=KBX0ylUDfXo">source</a>