I do not believe in immortality of the individual, and I consider ethics to be an exclusively human concern with no superhuman authority behind it.

Anybody who really wants to abolish war must resolutely declare himself in favor of his own country's resigning a portion of sovereignty in place of international institutions.

Whoever undertakes to set himself up as a judge of Truth and Knowledge is shipwrecked by the laughter of the gods.

You can't use an old map to explore a new world.

The real problem is in the hearts and minds of men. It is not a problem of physics but of ethics. It is easier to denature plutonium than to denature the evil spirit of man.

Once you can accept the universe as matter expanding into nothing that is something, wearing stripes with plaid comes easy.

Only the [Catholic] Church stood squarely across the path of Hitler’s campaign for suppressing truth. I never had any special interest in the Church before, but now I feel a great affection and admiration because the Church alone has had the courage and persistence to stand for intellectual truth and moral freedom. I am forced thus to confess that what I once despised I now praise unreservedly.