It is through good education that all the good in the world arises.

Act that your principle of action might safely be made a law for the whole world.

We can judge the heart of a man by his treatment of animals.

Sincerity is the indispensable ground of all conscientiousness, and by consequence of all heartfelt religion.

The question is not so much whether there is life on Mars as whether it will continue to be possible to live on Earth

For how is it possible, says that acute man, that when a concept is given me, I can go beyond it and connect with it another which is not contained in it, in such a manner as if that latter necessarily belonged to the former?

A lie is the abandonment and, as it were, the annihilation of the dignity by man.