It's been three and a half years since the Dow Jones fell 10% from a recent high. 

That's the third-longest streak without a 10% dip in the last 100 years. 

In this video, Motley Fool analyst Morgan Housel sits down with Matt Trogdon to discuss why this matters. In short, the longer a bull market lasts, the more surprising -- and painfull -- the bear will be when it eventually arrives.