Gustav Theodor Fechner’s immediate concern was with outer psychophysics, the functional dependence of mental intensity upon stimulus intensity. Fechnerian psychophysics was experimental in that it varied stimulus conditions quantitatively. Wilhelm Wundt’s “New Psychology” was in fact two psychologies—one fairly new, the other really quite old. As was only natural for a Gelehrter of his day, Wundt considered that psychology is properly the study of sensations, that is, of their genesis in stimulation, of their vicissitudes, and of their interconnections in consciousness. A great part of the attraction of Wundt’s “New Psychology” was that it was based upon the “experimental method”. Wundt noted that there is one respect in which the method of psychology must differ fundamentally from that of physics. Physics is based upon the method of external observation. Psychology, by contrast, must be based upon a method of internal observation; it must be based, in short, upon the method of introspection.