The next world war will be fought with stones.

The only sure way to avoid making mistakes is to have no new ideas.

I think that only daring speculation can lead us further and not accumulation of facts.

I am an adherent of the ideal of democracy, although I well know the weaknesses of the democratic form of government. Social equality and economic protection of the individual appeared to me always as the important communal aims of the state. Although I am a typical loner in daily life, my consciousness of belonging to the invisible community of those who strive for truth, beauty, and justice has preserved me from feeling isolated.

The only way to escape the personal corruption of praise is to go on working. One is tempted to stop and listen to it. The only thing is to turn away and go on working. Work. There is nothing else.

I believe we are here to do good. It is the responsibility of every human being to aspire to do something worthwhile, to make the world a better place than the one we found.

[O]nly if every individual strives for truth can humanity attain a happier future; the atavisms in each of us that stand in the way of a friendlier destiny can only thus be rendered ineffective.