Humor and knowledge are the two great hopes of our culture.
Most of the vices and mortal sins condemned today correspond to inclinations that were purely adaptive or at least harmless in primitive man
Just thinking that my dog loves me more than I love him, I feel shame.
All scientific knowledge to which man owes his role as master of the world arose from playful activities.
Man has been driven out of the paradise in which he could trust his instincts.
The instinctive need to be the member of a closely knit group fighting for common ideals may grow so strong that it becomes inessential what these ideals are.