If you want to move mountains, you just go move mountains. If you don't have a big enough shovel, you get some friends to help you. If you have the enthusiasm to charge ahead, you can do all sorts of things. Some things you can't do. You can't invent a perpetual motion machine. You've got to select your targets. But people can do so much more than they realize.

Paul MacCready Interview, Engineer of the Century, January 12, 1991, Pasadena, California