The discipline -- "It tells you where to carve the joints" -- What is a model? How does it work? -- The invisible hand and the pin factory -- How the dismal science got its name -- The underground river -- Spillovers and other accommodations -- The Keynesian revolution and the modern movement -- "Mathematics is a language" -- When economics went high-tech -- The residual and its critics -- The infinite-dimensional spreadsheet -- Economists turn to rocket science, and "model" becomes a verb -- New departures -- "That's stupid!" -- In Hyde Park -- The U-turn -- The keyboard, the city, and the world -- Recombinations -- Crazy explanations -- At the ski lift -- "Endogenous technological change" -- Conjectures and refutations -- A short history of the cost of lighting -- The ultimate pin factory -- The invisible revolution -- Teaching economics.