Watching him on News-Hour today, interesting that he said it was Asimov's sci-fi Foundation novels and psycho history that made him want to be an economist. I, somewhat embarrassingly, said exactly the same thing in my grad school essays. The idea that you could use mathematics to not only understand but also to shape society. In some ways, its amazing how far we've come toward achieving Asimov's vision, on the other hand, it's also notable how very far away we are as well.
The intro to my essay:
Issac Asimov, the science fiction writer, once envisioned a world where a mathematician invented a science called psychohistory that allowed him to foretell and therefore improve the course of human events. When I was younger, this fascinated me. However, it was not until I took freshman economics in college that I realized this was not all fantasy. By studying economics, I could apply my training in abstract math and theoretical computer science to something beyond the world of academia. The field of economics provides a window where my interests and abilities could be applied to research that has direct impact on the lives of so many people.Heh, also gratuitously mentioned "such as those from Paul Krugman’s graduate International Economics class which I audited." Interesting to read these old essays, made readily available by Vista search.