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.

The single most important decision any of us will ever make is whether or not to believe the universe is friendly.

Pure mathematics is, in its way, the poetry of logical ideas. ... [By seeking] logical beauty spiritual formulas are discovered necessary for the deeper penetration into the laws of nature.

I always have a high regard for the individual and have an insuperable distaste for violence and clubmanship. All these motives made me into a passionate pacifist and anti-militarist. I am against any nationalism, even in the guise of mere patriotism. Privileges based on position and property have always seemed to me unjust and pernicious, as did any exaggerated personality cult.

I have only two rules which I regard as principles of conduct. The first is: Have no rules. The second is: Be independent of the opinion of others.

I became more and more convinced that even nature could be understood as a relatively simple mathematical structure.

It is strange to be known so universally and yet to be so lonely.