Denis Diderot

Posterity for the philosopher is what the other world is for the religious man.

Passions destroy more prejudices than philosophy does.

One declaims endlessly against the passions; one imputes all of man's suffering to them. One forgets that they are also the source of all his pleasures.

Watch out for the fellow who talks about putting things in order! Putting things in order always means getting other people under your control.

Only God and some few rare geniuses can keep forging ahead into novelty.

There is less harm to be suffered in being mad among madmen than in being sane all by oneself.

Anyone who takes it upon himself, on his private authority, to break a bad law, thereby authorizes everyone else to break the good ones.

Isn’t it better to have men being ungrateful than to miss a chance to do good?

Bad company is as instructive as debauchery: one is indemnified for the loss of innocence by the loss of prejudice.

Fanaticism is just one step away from barbarism.

Virtue is praised but hated. People run away from it, for it is ice-cold and in this world you must keep your feet warm.

There are three principal means of acquiring knowledge . . . observation of nature, reflection, and experimentation.

Our observation of nature must be diligent, our reflection profound, and our experiments exact.

What has not been examined impartially has not been well examined. Skepticism is therefore the first step toward truth.

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 skepticism is the first step toward truth. It must be applied generally, because it is the touchstone.

There is no moral precept that does not have something inconvenient about it.

I can be expected to look for truth but not to find it.

All children are essentially criminal.

But how the devil do you think this could harm me?

Man will never be free until the last king is strangled with the entrails of the last priest.

We swallow greedily any lie that flatters us, but we sip only little by little at a truth we find bitter.

From fanaticism to barbarism is only one step.

Only passions, great passions, can elevate the soul to great things.

L’esprit de l’escalier.

And [with] the guts of the last priest

To say that man is made up of strength and weakness, of insight and blindness, of pettiness and grandeur, is not to draw up an indictment against him: it is to define him.

A man of letters may have a mistress who makes books, but he must have a wife who makes shirts.