Everything you say should be true, but not everything true should be said.
Doubt is not a very agreeable status, but certainty is a ridiculous one.
A witty saying proves nothing.
The most amazing and effective inventions are not those which do most honour to the human genius.
It is the first law of friendship that it has to be cultivated. The second is to be indulgent when the first law is neglected.
The opportunity for doing mischief is found a hundred times a day, and of doing good once in a year.