As we have said before, the immediate force of speculative literature hangs on practical opportuneness. It was not merely because Bacon and Hobbes and Locke had written certain books, that the Encyclopædists, who took up their philosophic succession, inevitably became a powerful political party, and multiplied their adherents in an increasing proportion as the years went on. From various circumstances the attack acquired a significance and a weight in France which it had never possessed in England. For one thing, physical science had in the interval taken immense strides. This both dwarfed the sovereignty of theology and theological metaphysics, and indirectly disposed men's minds for non-theological theories of moral as well as of physical phenomena. In France, again, the objects of the attack were inelastic and unyielding. Political speculation in England followed, and did not precede, political innovation and reform. In France its light played round institutions which were too deeply rooted in absolutism and privilege to be capable of substantial modification. Deism was comparatively impotent against the Church of England, first, because it was an intellectual movement, and not a social one; second, because the constitutional doctrines of the church were flexible. Deism in the hands of its French propagators became connected with social liberalism, because the Catholic church in those days was identified with all the ideas of repression. And the tendencies of deism in France grew more violently destructive, not only because religious superstition was grosser, but because that superstition was incorporated in a strong and inexpansible social structure.
"It would be a mistake," wrote that sagacious and well-informed observer, D'Argenson, so early as 1753, "to attribute the loss of religion in France to the English philosophy, which has not gained more than a hundred philosophers or so in Paris, instead of setting it down to the hatred against the priests, which goes to the very last extreme. All minds are turning to discontent and disobedience, and everything is on the high road to a great revolution, both in religion and in government. And it will be a very different thing to that rude Reformation, a medley of superstition and freedom, which came to us from Germany in the sixteenth century! As our nation and our century are enlightened in so very different a fashion, they will go whither they ought to go; they will banish every priest, all priesthood, all revelation, all mystery." This, however, only represents the destructive side of the vast change which D'Argenson then foresaw, six-and-thirty years before its consummation. That change had also a constructive side. If one of its elements was hate, another and more important element was hope. This constructive and reforming spirit which made its way in the intelligence of the leading men in France from 1750 to 1789, was represented in the encyclopædic confederation, and embodied in their forty folios. And, to return to our first point, it was directly and inseparably associated with the philosophy of Bacon and Locke. What is the connection between their speculations and a vehement and energetic spirit of social reform? We have no space here to do more than barely hint the line of answer.