The physiologic doctrine of the physical basis of mind is now established beyond dispute, although some of the ardent philosophers of the Platonic school still regard mind as an entity, and view it and consider it apart from its habitat—the brain.
This change in physiologic views has been brought about by the advent of physical methods of inquiry, which, under the name of the new psychology, promises to give us a substantial and real basis from which we may proceed in our excursion into the labyrinths of reason. The bearings of psycho-physics upon the study of mind, together with the empiric observations of the past ages, demonstrate that physiologic laws underlie mental phenomena—that mind reposes upon a nervous property sustained, like every other physical power, by nutrition. It shows, further, that the plasticity of the mind may be impaired in its full functioning by innutrition or malnutrition as well as