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 the conditions of modern life the rule is absolute, the race which does not value trained intelligence is doomed. Not all your heroism, not all your social charm, not all your wit, not all your victories on land or at sea, can move back the finger of fate. To-day we maintain ourselves. To-morrow science will have moved forward yet one more step, and there will be no appeal from the judgment which will then be pronounced on the uneducated.

To see what is general in what is particular, and what is permanent in what is transitory, is the aim of scientific thought.

People make the mistake of talking about 'natural laws.' There are no natural laws. There are only temporary habits of nature.

It is not paradox to say that in our most theoretical moods we may be nearest to our most practical applications.

The motive of success is not enough.

I consider Christian theology to be one of the great disasters of the human race.