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 the ardour of the
disciple pressed objections home with a trenchancy that is very unlike
the sage distillations of the master. It was from Shaftesbury, however,
that he borrowed common sense as a philosophic principle. Shaftesbury
had indirectly drawn it from Locke, and through Hutcheson it became the
source and sponsor of the Scottish philosophy of that century. This was
a weapon exactly adapted for dealing with a theology that was
discredited in the eyes of all cool observers by the hysterical
extravagances of one set of religionists, and the factious pretensions
of their rivals. And no other weapon was at hand. The historic or
critical method of investigation was impossible, for the age did not
possess the requisite learning. The indirect attack from the side of
physical science was equally impossible. The bearing of Newton's great
discovery on the current conceptions of the Creator and the supposed
system of the divine government, was not yet fully realised. The other
scientific ideas which have since made the old hypothesis less credible,
were not at that time even conceived.

Diderot did indeed perceive even so early as this that the controversy