When you sit with a nice girl for two hours, it seems like two minutes; when you sit on a hot stove for two minutes, it seems like two hours. That's relativity.

If you took half of something and continued to take half of that half and so on, you would never reach an end.

All the fifty years of conscious brooding have brought me no closer to answer the question, "What are light quanta?" Of course today every rascal thinks he knows the answer, but he is deluding himself.

It is characteristic of the military mentality that non-human factors ... are held essential, while the human being, his desires and thoughts-in short, the psychological factors-are considered as unimportant and secondary.

Warfare cannot be humanized.

You think you have troubles with mathematics . . . I assure you mine are still bigger.

I have made no secret, either privately or publicly, of any sense of outrage over officially enforced military and war service. I regard it as a duty of conscience to fight against such barbarous enslavement of the individual with every means available.