I regret that it has been necessary for me in this lecture to administer a large dose of four-dimensional geometry. I do not apologize, because I am really not responsible for the fact that nature in its most fundamental aspect is four-dimensional. Things are what they are.

In formal logic, a contradiction is the signal of defeat, but in the evolution of real knowledge it marks the first step in progress toward a victory.

When success turns a man's head he faces failure

Human life is driven forward by its dim apprehension of notions too general for its existing language.

...the self-satisfied dogmatism with which mankind at each period of its history cherishes the delusion of the finality of existing modes of knowledge.

Almost all new ideas have a certain aspect of foolishness when they are first produced.

Life is an offensive, directed against the repetitious mechanism of the Universe.