I ceased in the year 1764 to believe that one can convince one’s opponents with arguments printed in books. It is not to do that, therefore, that I have taken up my pen, but merely so as to annoy them, and to bestow strength and courage on those on our own side, and to make it known to the others that they have not convinced us.

There is no greater impediment to progress in the sciences than the desire to see it take place too quickly.

The fruits of philosophy are the important thing, not the philosophy itself. When we ask the time, we don't want to know how watches are made.

A book which, above all others in the world, should be forbidden, is a catalogue of forbidden books.

People who have read a good deal rarely make great discoveries. I do not say this in excuse of laziness, but because invention presupposes an extensive independent contemplation of things.

Many things about our bodies would not seem to us so filthy and obscene if we did not have the idea of nobility in our heads.

As the few adepts in such things well know, universal morality is to be found in little everyday penny-events just as much as in great ones. There is so much goodness and ingenuity in a raindrop that an apothecary wouldn't let it go for less than half-a-crown.