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.

I believe that present day civilized man suffers from insufficient discharge of his aggressive drive

All scientific knowledge to which man owes his role as master of the world arose from playful activities.

The neuro-physiological organization which we call instinct functions in a blindly mechanical way, particularly apparent when its function goes wrong.

One of the most dangerously vicious circles menacing the continued existence of all mankind arises through that grim striving for the highest possible position within the ranked order, in other words, the reckless pursuit of power which combines with an insatiable greed of neurotic proportions that the results of acquired power confer.

Truth in science can be defined as the working hypothesis best suited to open the way to the next better one.

Just thinking that my dog loves me more than I love him, I feel shame.