.. free and responsible development of the individual, so that he may place his powers freely and gladly in the service of all mankind. There is no room in this for the divinization of a nation, of a class, let alone of an individual. Are we not all children of one father, as it is said in religious language?

For an idea that does not first seem insane, there is no hope.

One must console oneself with the thought that time has a sieve through which most of these important things run into the ocean of oblivion and what remains after this selection is often still trite and bad.

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.

The difference between stupidity and genius is that genius has its limits.

Since our inner experiences consist of reproductions, and combinations of sensory impressions, the concept of a soul without a body seem to me to be empty and devoid of meaning.

Anyone who thinks science is trying to make human life easier or more pleasant is utterly mistaken.