Without deep reflection one knows from daily life that one exists for other people.

Physics is essentially an intuitive and concrete science. Mathematics is only a means for expressing the laws that govern phenomena.

The relativity principle in connection with the basic Maxwellian equations demands that the mass should be a direct measure of the energy contained in a body; light transfers mass. With radium there should be a noticeable diminution of mass. The idea is amusing and enticing; but whether the Almighty is laughing at it and is leading me up the garden path -- that I cannot know.

The essentials of being a person of my type lies precisely in what they think and how they think, not in what they do. Your thoughts shape you.

How many people are trapped in their everyday habits: part numb, part frightened, part indifferent? To have a better life we must keep choosing how we are living.

Only the Catholic Church protested against the Hitlerian onslaught on liberty. Up till then I had not been interested in the Church, but today I feel a great admiration for the Church, which alone has had the courage to struggle for spiritual truth and moral liberty

I am absolutely convinced that no wealth in the world can help humanity forward, even in the hands of the most devoted worker in this cause. The example of great and pure characters is the only thing that can produce fine ideas and noble deeds. Money only appeals to selfishness and always tempts its owners irresistibly to abuse it