Marshall’s great books on progress and politics were never written. His fourth major work was to be Progress: Its Economic Conditions, but he never found time in his crowded life to convert the notes into the treatise. The third volume of his Principles, he announced in 1907, was to deal with ‘the economic functions of Government’, thereby indicating his conviction that, alongside micro (‘the modern conditions of industry and trade’) and macro (‘credit and employment’)1 the student of economics should in some measure also be a student of political economy. As, of course, Adam Smith and so many of the English classicals had been. And Plato, who, as Keynes reminds us, inevitably captured the imagination of the philosopher missionary: ‘One day in his eighty-second year he said that he was going to look at Plato’s Republic, for he would like to try and write about the kind of Republic that Plato would wish for, had he lived now.’2 But the great interdisciplinary account of Economy and Polity, Ethics and Society, had in the event this in common with the path-breaking dynamical synthesis of Growth and Betterment, Upgrading and Evolution, that it too never saw the light of day.