The Importance of Understanding the Strong Interaction

You couldn't even begin to think about a grand unified theory without first of all understanding the strong interaction. So we found the equations, and so you know what it is. And it turns out that those equations are very profoundly similar to their richer counterparts. Having these four theories with similar conceptual structure makes almost, is begging you to try to unify them. Of course, it involves a huge extrapolation, so a lot of things could go wrong. It's amazing it works as well as it does.