... on principle, it is quite wrong to try founding a theory on observable magnitudes alone. In reality the very opposite happens. It is the theory which decides what we can observe.

I wish to do something Great and Wonderful, but I must start by doing the little things like they were Great and Wonderful

That deep emotional conviction of the presence of a superior reasoning power, which is revealed in the incomprehensible universe, forms my idea of God.

The really valuable thing in the pageant of human life seems to me not the political state, but the creative, sentient individual, the personality; it alone creates the noble and the sublime, while the herd as such remains dull in thought and dull in feeling.

It is certainly true that principles cannot be more securely founded than on experience and consciously clear thinking.

From a certain temperature on, the molecules 'condense' without attractive forces; that is, they accumulate at zero velocity. The theory is pretty, but is there some truth in it.

Heroism on command, senseless violence, and all the loathsome nonsense that goes by the name of patriotism - how passionately I hate them!