Deliberate virtue is never worth much: The virtue of feeling or habit is the thing.

Some people feel with their heads and think with their hearts.

To do just the opposite is also a form of imitation.

The most successful tempters and thus the most dangerous are the deluded deluders.

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.

The highest point to which a weak but experienced mind can rise is detecting the weakness of better men.

Be attentive, feel nothing in vain, measure and compare: this is the whole law of philosophy.