Neither art thou the man to catch the fiend and hold him! [Ger., Du bist noch nicht der Mann den Teufel festzuhalten.

At all times it has not been the age, but individuals alone, who have worked for knowledge. It was the age which put Socrates to death by poison, the age which burnt Huss. The ages have always remained alike.

The man who acts never has any conscience; no one has any conscience but the man who thinks

I do not speak of what I cannot praise.

Everything factual is, in a sense, theory. The blue of the sky exhibits the basic laws of chromatics. There is no sense in looking for something behind phenomena: they are theory.

Three things are to be looked to in a building: that it stand on the right spot; that it is securely founded; that it be successfully executed.

Superstition is the poetry of life.