Does it not seem reasonable to claim that human behavior may be intelligently controlled or directed only in the light of intimate and exhaustive knowledge of the organism, its processes, and its relations to its environment? If this be true, how pitiably, how shamefully, inadequate is our knowledge even of ourselves! How few are those who have a sound, although meager, knowledge of the laws of heredity, of the primary facts of human physiology, of the principles of hygiene, of the chief facts and laws of mental life, including the fundamental emotions and their corresponding instinctive modes of action, the modifiability or educability of the individual and the important relations of varied sorts of experience and conduct, the laws of habit, the nature and role of the sentiments, the unnumbered varieties of memory and ideation, the chief facts of social life and their relations to individual experience and behavior. Not one person in a thousand has a knowledge of life and its conditions equal in adequacy for practical demands to his knowledge of those aspects of physical nature with which he is concerned in earning a livelihood. Even those of us who have dedicated our lives to the study of life are humble before our ignorance. But with a faith which can not be shaken, because we have seen visions and dreamed dreams, we insist that the knowledge which we seek and daily find is absolutely essential for the perfecting of educational methods; for the development of effective systems of bodily and mental hygiene; for the discovery, fostering and maintenance of increasingly profitable social relations and organizations. In a word, we believe that biology, of all sciences, can and must lead us in the path of social as contrasted with merely material progress; can and ultimately will so alter the relations of nations that war shall be as impossible as is peace to-day. Fortunately the biologist may depend, in his efforts to further the study of all aspects of life, not upon faith and hope alone, but also upon works, for already physiology and psychology have transformed our educational practices; and the medical sciences given us a great and steadily increasing measure of control over disease. At least two men, as different in intellectual equipment, habits of mind, and methods of inquiry as well could be, the one an American, the other an Englishman, have heralded the broadly comparative and genetic study of mind and behavior--let us call it Genetic Psychology--as the promise of a new era for civilization, because the essential condition of the intelligent and effective regulation of life.