We know nothing at all. All our knowledge is but the knowledge of schoolchildren. The real nature of things we shall never know.

Enjoying the joys of others and suffering with them-these are the best guides for man.

The pursuit of truth and beauty is a sphere of activity in which we are permitted to remain children all our lives.

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.

Playfullness is the essential feature of productive thought.

So I am living without fats, without meat, without fish, but am feeling quite well this way. It always seems to me that man was not born to be a carnivore.

Force always attracts men of low morality.