We must not conceal from ourselves that no improvement in the present depressing situation is possible without a severe struggle; for the handful of those who are really determined to do something is minute in comparison with the mass of the lukewarm and the misguided. And those who have an interest in keeping the machinery of war going are a very powerful body; they will stop at nothing to make public opinion subservient to their murderous ends.

There comes a point in your life when you need to stop reading other people's books and write your own.

However we select from nature a complex [of phenomena] using the criterion of simplicity, in no case will its theoretical treatment turn out to be forever appropriate (sufficient).... I do not doubt that the day will come when [general relativity], too, will have to yield to another one, for reasons which at present we do not yet surmise. I believe that this process of deepening theory has no limits.

Politics is a pendulum whose swings between anarchy and tyranny are fueled by perennially rejuvenated illusions.

Discussion and argument are essential parts of science; the greatest talent is the ability to strip a theory until the simple basic idea emerges with clarity.

I get the most joy in life out of music.

It is nothing short of a miracle that modern methods of teaching have not yet entirely strangled that sacred spirit of curiosity and inquiry, for this delicate plant needs freedom no less than stimulation.