Just as we outgrow a pair of trousers, we outgrow acquaintances, libraries, principles, etc., at times before they're worn out and times - and this is the worst of all - before we have new ones.

There are people who think that everything one does with a serious face is sensible.

One should never trust a person who, while assuring you of something, puts his hands on his heart.

We cannot remember too often that when we observe nature, and especially the ordering of nature, it is always ourselves alone we are observing.

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.

To many people virtue consists chiefly in repenting faults, not in avoiding them.

If another Messiah was born he could hardly do so much good as the printing-press.