The force of speculative literature always hangs on practical opportuneness.  The economic evils of monasticism, the increasing flagrancy and grossness of superstition, the aggressive factiousness of the ecclesiastics, the cruelty of bigoted tribunals—­these things disgusted and wearied the more enlightened spirits, and the English philosophy only held out an inspiring intellectual alternative.[29]

Nor was it accident that drew Diderot’s attention to Shaftesbury, rather than to any other of our writers.  That author’s essay on Enthusiasm had been suggested by the extravagances of the French prophets, poor fanatics from the Cevennes, who had fled to London after the revocation of the edict of Nantes, and whose paroxysms of religious hysteria at length brought them into trouble with the authorities (1707).  Paris saw an outbreak of the same kind of ecstasy, though on a much more formidable scale, among the Jansenist fanatics, from 1727 down to 1758, or later.  Some of the best attested miracles in the whole history of the supernatural were wrought at the tomb of the Jansenist deacon, Paris.[30] The works of faith exalted multitudes into convulsive transports; men and women underwent the most cruel tortures, in the hope of securing a descent upon them of the divine grace.  The sober citizen, whose journal is so useful a guide to domestic events in France from the Regency to the Peace of 1763, tells us the effect of this hideous revival upon public sentiment.  People began to see, he says, what they were to think of the miracles of antiquity.  The more they went into these matters, whether miracles or prophecies, the more obscurity they discovered in the one, the more doubt about the other.  Who could tell that they had not been accredited and established in remote times with as little foundation as what was then passing under men’s very eyes?  Just in the same way, the violent and prolonged debates, the intrigue, the tergiversation, which attended the acceptance of the famous Bull Unigenitus, taught shrewd observers how it is that religions establish themselves.  They also taught how little respect is due in our minds and consciences to the great points which the universal church claims to have decided.[31]

These are the circumstances which explain the rude and vigorous scepticism of Diderot’s first performances.  And they explain the influence of Shaftesbury over him.  Neither Diderot nor his contemporaries were ready at once to plunge into the broader and firmer negation to which they afterwards committed themselves.  No doubt some of the politeness which he shows to Christianity, both in the notes to his translation of Shaftesbury, and in his own Philosophic Thoughts, is no more than an ironical deference to established prejudices.  The notes to the Essay on Merit and Virtue show that Diderot, like all the other French revolters against established prejudice, had been deeply influenced by the shrewd-witted Montaigne.  But