At the beginning of the nineteenth century the French physician Cabanis was disposed to identify human personality with mere nervous organization reacting to physical impressions, and to look upon the brain as the organ for the production of mind. He soon, however, withdrew from this extreme position and expressed his conviction of the existence of an immortal spirit apart from the body. One might say that the brain is the instrument through which the mind manifests itself rather than the organ by which mind is excreted. Even so, it must be agreed that the relation between the psychic agent and the physical instrument is so close that physiology must take heed of mental phenomena and that psychology must not ignore the physical concomitants of mental processes. Hence arises a new branch of natural science, physiological psychology, or, as Fechner (1860), the disciple of Weber, called it, psycho-physics. Through this alliance between the study of the mind and the study of bodily functions the intelligence of the lower animals and its survival value, the mental growth of the child, mental deterioration in age and disease, and the psychological endowments of special classes or of individuals, became subjects for investigation. Now human psychology is recognized as contributing to various branches of anthropology, or the general study of man. Wilhelm Wundt, who, as already implied, had approached the study of the mind from the side of the natural sciences, established in 1875 at the University of Leipzig the first psycho-physical institute for the experimental study of mental phenomena. His express purpose was to analyze the content of consciousness into its elements, to examine these elements in their qualitative and quantitative differences, and to determine with precision the conditions of their existence and succession. Thus science after contemplating a wide range of outer phenomena--plants, animals, earth's crust, heavenly bodies, molecules and atoms--turns its attention with keen scrutiny inward on the thinking mind, the subjective process by which man becomes cognizant of all objective things.