We hope we have convinced you that the “ordinary business of life” is really quite extraordinary, if you stop to think about it, and that it can lead us to ask some very interesting and important questions.

In this book, we will describe the answers economists have given to these questions. But this book, like economics as a whole, isn’t a list of answers: it’s an introduction to a discipline, a way to address questions like those we have just asked. Or as Alfred Marshall, who described economics as a study of the “ordinary business of life,” put it: “Economics … is not a body of concrete truth, but an engine for the discovery of concrete truth.”

So let’s turn the key and start the ignition.