A thing is not proved just because no one has ever questioned it. What has never been gone into impartially has never been properly gone into. Hence scepticism is the first step toward truth. It must be applied generally, because it is the touchstone.
Denis DiderotAll things must be examined, debated, investigated without exception and without regard for anyone's feelings.
Denis DiderotThere is no true sovereign except the nation; there can be no true legislator except the people.
Denis DiderotThere comes a moment during which almost every girl or boy falls into melancholy; they are tormented by a vague inquietude which rests on everything and finds nothing to calm it. They seek solitude; they weep; the silence to be found in cloister attracts them: the image of peace that seems to reign in religious houses seduces them. They mistake the first manifestations of a developing sexual nature for the voice of God calling them to Himself; and it is precisely when nature is inciting them that they embrace a fashion of life contrary to nature's wish.
Denis DiderotIf there were a reason for preferring the Christian religion to natural religion, it would be because the former offers us, on the nature of God and man, enlightenment that the latter lacks. Now, this is not at all the case; for Christianity, instead of clarifying, gives rise to an infinite multitude of obscurities and difficulties.
Denis Diderot