When one compares the talents one has with those of a Leibniz, one is tempted to throw away one's books and go die quietly in the dark of some forgot… - Denis Diderot

Man was born to live with his fellow human beings. Separate him, isolate him, his character will go bad, a thousand ridiculous affects will invade his heart, extravagant thoughts will germinate in his brain, like thorns in an uncultivated land.

We do not know nature; causes hidden in her breast might have produced everything. In your turn, observe the polyp of Trembley: does it not contain in itself the causes which bring about regeneration? Why then would it be absurd to think that there are physical causes by reason of which everything has been made, and to which the whole chain of this vast universe is so necessarily bound and held that, nothing which happens, could have failed to happen,—causes, of which we are so invincibly ignorant that we have had recourse to a God, who, as some aver, is not so much as a logical entity? Thus to destroy chance is not to prove the existence of a supreme being, since there may be some other thing which is neither chance nor God—I mean, nature. It follows that the study of nature can make only unbelievers; and the way of thinking of all its more successful investigators proves this.

The enjoyment of freedom which could be exercised without any motivation would be the real hallmark of a maniac.