"It is customary to say that the scientist's ultimate aim is to predict and control. This is a summary statement that psycholoigsts frequently like to quote in characterizing their own aspirations. Yet curiously enough, psychologists rarely credit the human subjects in their experiments with having similar aspirations. It is as though the psychologist were saying to himself, 'I, being a psychologist, and therefore a scientist, am performing this experiment in order to improve the prediction and control of certain human phenomena; but my subject, being merely a human organism, is obviously propelled by inexorable drives welling up within him, or else he is in gluttonous pursuit of sustenance and shelter.' " G.A. Kelly, A theory of personality, New York, W.W. Norton, 1963, p. 5.