The first edition of this work (part 1 of the present edition) was published in 1909. "The substance of part I ... was given in lectures delivered in the University of Oxford during Michaelmas term, 1908. The substance of part II was given in lectures delivered in the University of Chicago during December, 1929 ... Part II forms a thesis submitted ... [to] the University of London... for the degree of doctor of science in economics. "-Pref. to edition of 1930.