We may say then that directly or indirectly the instincts are the prime movers of all human activity; by the conative or impulsive force of some instinct (or of some habit derived from an instinct), every train of thought, however cold and passionless it may seem, is borne along toward its end, and every bodily activity is initiated and sustained. The instinctive impulses determine the ends of all activities and supply the driving-power by which all mental activities are sustained; and all the complex intellectual apparatus of the most highly developed mind is but a means toward those ends, is but the instrument by which these impulses seek their satisfactions.... These impulses are the mental forces that maintain and shape all the life of individuals and societies, and in them we are confronted with the central mystery of life and mind and will. This is all very good so far as it goes. But I confess that I am somewhat at loss to know just what it explains so far as crowd-behavior is concerned. Do these instincts and sentiments operate the same under all social conditions? Are some of them suppressed by society and forced to seek their satisfaction in roundabout ways? If so, how? Moreover, I fail to find in present-day social psychology, any more than in the writings of Herbert Spencer, Sumner, Ward, and others, any clear distinction between the characteristic behavior of crowds and other forms of social activity. Only the school of Le Bon has shown any definite appreciation of these facts. It is to Le Bon, therefore, in spite of the many and just criticisms of his work, that we must turn for a discussion of the crowd as a problem apart from social psychology in general. Le Bon saw that the mind of the crowd demanded special psychological study, but many of the psychological principles which he used in solving the problem were inadequate to the task. Certain of his conclusions were, therefore, erroneous. Since the close of the nineteenth century, however, psychology has gained much insight into the secret springs of human activity. Possibly the most significant achievement in the history of this science is Freud's work in analytical psychology. So much light has been thrown upon the unconscious by Freud and other analytical psychologists, that psychology in all its branches is beginning to take some of Freud's discoveries into account. Strictly speaking, psychoanalysis is a therapeutic method. It has, however, greatly enriched our knowledge of mental pathology, and thus much of its data has become indispensable to general psychology and to social psychology in particular.