... mathematics ... affords the exact natural sciences a certain measure of certainty, to which without mathematics they could not attain.

Non-cooperation in military matters should be an essential moral principle for all true scientists ...

... a person who is religiously enlightened appears to me to be one who has, to the best of his ability, liberated himself from the fetters of his selfish desires and is preoccupied with thoughts, feelings, and aspirations to which he clings because of their superpersonal value.

I think and think for months and years. Ninety-nine times, the conclusion is false. The hundredth time I am right.

As to science, we may well define it for our purpose as "methodical thinking directed toward finding regulative connections between our sensual experiences."

Science is an attempt to make the chaotic diversity of our sense-experience correspond to a logically uniform system of thought.

We scientists, whose tragic destination has been to help in making the methods of annihilation more gruesome and more effective, must consider it our solemn and transcendent duty to do all in our power in preventing these weapons from being used for the brutal purpose for which they were invented.

Is it not a terrible thing to be forced by society to do things which all of us as individuals regard as abominable crimes?

The difference between what the most and the least learned people know is inexpressibly trivial in relation to that which is unknown.

How vile and despicable war seems to me! I would rather be hacked to pieces than take part in such an abominable business.