Keynes, in the much–quoted concluding paragraph of the General Theory, put forward his own incisive formulation of the view that ‘the ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood’. ‘Indeed’, he went on to stress, ‘the world is ruled by little else’: ‘Practical men, who believe themselves to be quite exempt from any intellectual influences, are usually the slaves of some defunct economist. Madmen in authority, who hear voices in the air, are destilling their frenzy from some academic scribbler of a few years back. I am sure that the power of vested interests is vastly exaggerated compared with the gradual encroachment of ideas’. This process, concluded Keynes, has a built–in–time–lag, ‘for in the field of economic and political philosophy there are not many who are influenced by new theories after they are twenty–five or thirty years of age, so that the ideas which civil servants and politicians and even agitators apply to current events are not likely to be the newest. But, soon or late, it is ideas, not vested interests, which are dangerous for good and evil’.

As seen in part I (chapter 1) above, this vivid and carefully drawn picture of ‘consciously formulated ideas acting as a driving force effecting transitions from social state to social state’ belongs to a distinguished and numerous family in the history of ideas.