It is a good morning exercise for a research scientist to discard a pet hypothesis every day before breakfast. It keeps him young.

Barking dogs may occasionally bite, but laughing men hardly ever shoot!

Truth in science can be defined as the working hypothesis best suited to open the way to the next better one.

The neuro-physiological organization which we call instinct functions in a blindly mechanical way, particularly apparent when its function goes wrong.

I believe that both art and the human striving for cognitive comprehension are manifest forms of the grand game in which nothing more is stipulated than the game's rules; both art and actively solicited perceptions are but special cases of the recurring creative act to which we owe our existence.

Evil, by definition, is that which endangers the good, and the good is that which we perceive as a value.

The instinctive need to be the member of a closely knit group fighting for common ideals may grow so strong that it becomes inessential what these ideals are.