Some years ago, an American psychologist, Abraham Maslow, felt the same kind of instinctive revolt against the 'atmosphere' of Freudian psychology, with its emphasis on sickness and neurosis, and decided that he might obtain some equally interesting results if he studied extremely healthy people. He therefore looked around for the most cheerful and well-adjusted people he could find, and asked for their co-operation in his studies. he soon discovered and interesting fact: that most extremely healthy people frequently experience of intense affirmation and certainty; Maslow called these 'peak experiences.' No one had made this discovery before because it had never struck anyone that a science calling itself 'psychology' and professing to be a science of the human mind (not merely the sick mind), ought to form its estimate of human beings by taking into account healthy minds as well as sick ones. A sick man talks obsessively about his illness; a healthy man never talks about his health; for as Pirandello points out, we take happiness for granted, and only begin to question life when we are unhappy. Hence no psychologist ever made this simple and obvious discovery about peak experiences.
Colin Wilson in Introduction to the New Existentialism, p. 15 (1966)