When asked which five books have inspired him the most, Krugman cited a science fiction novel, Foundation Trilogy (by Isaac Asimov), and a philosophical treatise, An Enquiry Concerning Human Understanding (by David Hume) as well as three classics in the field of Economics: The General Theory of Employment, Interest and Money (by John Maynard Keynes), Essays in Persuasion (by John Maynard Keynes), and Essays in Economics (by James Tobin).