The primitive man recognized within himself a something which he could not see but could feel; something elusive, impulsive, and turbulent. He felt the air all around him. The psychoanalysts more than any other present-day group utilize the principle of dynamic urge. They recognize the possibilities of many instincts but find in the conflict between the native strivings of the individual and the always opposed environment a sufficient basis for everything we think and feel and do. Sigmund Freud’s emphasis on the harmful results of suppressed sexual desires and his insistence on erotic experience as the ultimate purpose of human behaviour have done much to reveal the futility of the taboos placed on sex by civilized society. The experimental limitation upon the number of demonstrable, unmodified, and unlearned human activities is now generally accepted by the majority of psychologists.