"The neurotic is a person who has discovered the meaning of life, but not the purpose."

"The tendency to aggression is an innate, independent, instinctual disposition in man... it constitutes the most powerful obstacle to culture."

"What is common in all these dreams is obvious. They are all wish-fulfillments."

"Man's most precious possession is the capacity for love and work."

"The greater the progress of science, the more it pushes back the limits of the unknown, but also the more it reveals the immensity of the unknown."