It is true that the grasping of truth is not possible without empirical basis. However, the deeper we penetrate and the more extensive and embracing our theories become the less empirical knowledge is needed to determine those theories.

Keep on sowing your seed, for you never know which will grow - perhaps it all will.

We come now to the question: what is a priori certain or necessary, respectively in geometry (doctrine of space) or its foundations? Formerly we thought everything; nowadays we think nothing. Already the distance-concept is logically arbitrary; there need be no things that correspond to it, even approximately.

It almost seems to me that man was not born to be a carnivore.

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.

Science is the process of making obviously erroneous ideas less obviously erroneous.

The foundation of morality should not be made dependent on myth nor tied to any authority lest doubt about the myth or about the legitimacy of the authority imperil the foundation of sound judgment and action.