 This figure from QWFP at Wikimedia.org, the source is down here in the lower left, shows the history of the size of the world economy per person. So more dollars and more economic activity goes up against time starting in the year 1500 on the left and running up to 2000 and then growth has continued. And what you'll notice is that the economy per person has grown fairly steadily, even with all the wars, even with all the plagues and everything else, we've seen growth. This growth looks like what we call an exponential, except what we know is that an exponential goes to infinity and we are confident that you can't make something infinite. The really interesting questions are whether the future eventually flattens out or whether the future might flatten out and then come down gradually, or whether the future might go way up and then crash into something horrible. And this is a subject that has to interest a lot of people in a lot of ways.