Looking back on the course of the inquiry, we note how the history of the idea has been connected with the growth of modern science, with the growth of rationalism, and with the struggle for political and religious liberty. The precursors (Bodin and Bacon) lived at a time when the world was consciously emancipating itself from the authority of tradition and it was being discovered that liberty is a difficult theoretical problem. The idea took definite shape in France when the old scheme of the universe had been shattered by the victory of the new astronomy and the prestige of Providence, CUNCTA SUPERCILIO MOUENTIS, was paling before the majesty of the immutable laws of nature. There began a slow but steady reinstatement of the kingdom of this world. The otherworldly dreams of theologians, ceux qui reniaient la terre pour patrie, which had ruled so long lost their power, and men's earthly home again insinuated itself into their affections, but with the new hope of its becoming a place fit for reasonable beings to live in. We have seen how the belief that our race is travelling towards earthly happiness was propagated by some eminent thinkers, as well as by some "not very fortunate persons who had a good deal of time on their hands." And all these high-priests and incense-bearers to whom the creed owes its success were rationalists, from the author of the Histoire des oracles to the philosopher of the Unknowable. EPILOGUE In achieving its ascendency and unfolding its meaning, the Idea of Progress had to overcome a psychological obstacle which may be described as THE ILLUSION OF FINALITY. It is quite easy to fancy a state of society, vastly different from ours, existing in some unknown place like heaven; it is much more difficult to realise as a fact that the order of things with which we are familiar has so little stability that our actual descendants may be born into a world as different from ours as ours is from that of our ancestors of the pleistocene age. The illusion of finality is strong. The men of the Middle Ages would have found it hard to imagine that a time was not far off in which the Last Judgement would have ceased to arouse any emotional interest. In the sphere of speculation Hegel, and even Comte, illustrate this psychological limitation: they did not recognise that their own systems could not be final any more than the system of Aristotle or of Descartes. It is science, perhaps, more than anything else--the wonderful history of science in the last hundred years--that has helped us to transcend this illusion.