which were frequent in Diderot's later years, and whose assurance of
his materialistic atheism would be complete had they not been too
exclamatory for settled conviction. He contents himself with
glorifying the passions, to the annulling of all ethical standards.
On this point at least his convictions were stable, for long afterward
he writes thus to Mademoiselle Voland:--"The man of mediocre passion
lives and dies like the brute.... If we were bound to choose between
Racine, a bad husband, a bad father, a false friend, and a sublime
poet, and Racine, good father, good husband, good friend, and dull
worthy man, I hold to the first. Of Racine the bad man, what remains?
Nothing. Of Racine the man of genius? The work is eternal."

About 1747 he produced an allegory, 'Promenade du Sceptique.' This
French 'Pilgrim's Progress' scoffs at the Church of Rome for denying
pleasure, then decries the pleasures of the world, and ends by
asserting the hopeless uncertainty of the philosophy which both scoffs
at the Church and decries worldly pleasure. At this period he was
evidently inclined to an irregular attack on the only forms of
Christianity familiar to him, asceticism and pietism.

In 1749 Diderot first showed himself a thinker of original power, in
his Letter on the Blind. This work, 'Lettre sur les Avengles a l'Usage
de Ceux qui Voient' (Letter on the Blind for the Use of Those who See)
opened the eyes of the public to Diderot's peculiar genius, and the
eyes of the authorities to the menace in his principles. The result
was his imprisonment, and from that the spread of his views. His
offense was, that through his ingenious supposition of the mind
deprived of its use of one or more of the bodily senses, he had shown
the relativity of all man's conceptions, and had thence deduced
the relativity, the lack of absoluteness, of all man's ethical
standards--thus invalidating the foundations of civil and social
order. The broad assertion that Diderot and his philosophic group
caused the French Revolution has only this basis, that these men
were among the omens of its advance, feeling its stir afar but not
recognizing the coming earthquake. Yet it may be conceded that Diderot
anticipated things great and strange; for his mind, although neither
precise nor capable of sustained and systematic thought, was amazingly
original in conception and powerful in grasp. The mist, blank to his
brethren, seems to have wreathed itself into wonderf