I was 19 years old when 9/11 happened, and I didn’t know what to make of it. Now, I think I do. It took a few weeks after the terror attacks for our government to launch an invasion of one country. Not the country in which the attacks were planned (Germany), and not the country from which most of the attackers came (Saudi Arabia). But at least we did invade the country that was ruled by a regime that was harboring the terror network itself. Our troops are still there, presumably contemplating the lessons of history.