An Honest politician will not be tolerated by a democracy unless he is very stupid ... because only a very stupid man can honestly share the prejudices of more than half the nation.

Be scrupulously truthful, even if the truth is inconvenient, for it is more inconvenient when you try to conceal it.

Science, by itself cannot, supply us with an ethic.

... the word "theory" ... was originally an Orphic word, which Cornford interprets as "passionate sympathetic contemplation" ... For Pythagoras, the "passionate sympathetic contemplation" was intellectual, and issued in mathematical knowledge ... To those who have reluctantly learnt a little mathematics in school this may seem strange; but to those who have experienced the intoxicating delight of sudden understanding that mathematics gives, from time to time, to those who love it, the Pythagorean view will seem completely natural.

It is not my prayer and humility that you cause things to go as you wish, but by acquiring a knowledge of natural laws.

If you wish to be happy yourself, you must resign yourself to seeing others also happy.

The desire to understand the world and the desire to reform it are the two great engines of progress, without which human society would stand still or retrogress.