We must be prepared to make the same heroic sacrifices for the cause of peace that we make ungrudgingly for the cause of war.

It may be possible to fight intolerance, stupidity, and fanaticism seperately, but when they come together there is no hope.

An evening everyone agrees, is a lost evening.

Academic chairs are many, but wise and noble teachers are few; lecture-rooms are numerous and large, but the number of young people who genuinely thirst after truth and justice is small

Just because you believe in something does not mean that it is true.

(Reply on what constitutes scientific proof:)"The question is much too difficult for me.

It would be better if you began to teach others only after you yourself have learned something.