Alfred Marshall's introduction of the ‘Giffen Good’ case appears puzzling, if only because it was not discussed by Robert Giffen. This article suggests that the analytical framework which Marshall used to discuss the case owed a good deal to the work of W.S. Jevons. The precise argument, however, was introduced as a rhetorical device to defend the notion of consumer surplus (against J.S. Nicholson) and to criticize the advocacy of tariff reform (by W.A.S. Hewi