If everybody lived as I do, surely the writing of romance novels would never have come into being.

We can understand almost anything, but we can't understand how we understand.

Nature conceals her mystery by her essential grandeur.

No idea is conceived in our mind independent of our five senses [i.e., no idea is divinely inspired].

Great spirits have always encountered opposition from mediocre minds. The mediocre mind is incapable of understanding the man who refuses to bow blindly to conventional prejudices and chooses instead to express his opinions courageously and honestly.

A scientist is a mimosa when he himself has made a mistake, and a roaring lion when he discovers a mistake of others.

Whether or not you can observe a thing depends upon the theory you use. It is the theory which decides what can be observed.