PHYSIOLOGICAL PSYCHOLOGY 77 



same nerve always originates the same sensation. " Miiller's law of 

 the specific energies marks an advance of the greatest importance . . . 

 and is, in a certain sense, the empirical exposition of the theoretical dis- 

 cussion of Kant on the nature of the intellectual process in the human 

 mind." 7 Of course, Miiller's views drew criticism, 8 but for us now the 

 point is that they started activity which, bit by bit, built physiological 

 psychology into a science. 



Fortunate in his disciples— Briicke, Helmholtz, du Bois Beymond, 

 Ludwig, Czermak, Donders (most teachers would forego all personal 

 glory gladly to obtain such human material)— Miiller enjoyed luck in 

 the contemporary course of events. For a science more developed and 

 surer of itself than physiology was about to join forces with the newer 

 branch. Magnus, his Berlin colleague in physics, became the focal 

 point of a movement to which Mitscherlich, Liebig, Ohm, F. Neumann, 

 and the brothers Weber all contributed, the first and last notably. The 

 sobering drill of hard, experimental fact gained its recognition here. 

 Or, as we say in philosophy, the prose of Kant was added to the 

 romance of Schelling. For physiological psychology the steadying in- 

 fluence came most by way of Ernst Heinrich Weber, of Leipzig (1795- 

 1878). Weber, with his younger brothers, Wilhelm and Eduard, 

 worked from the first along distinctively modern lines. The specula- 

 tive thought, prevalent in his youth, seems to have passed over his 

 head. Exact experimental methods came naturally, as it were, to him 

 and to his brothers. From early life they employed mechanical and 

 mathematical analyses in dealing with physical, physiological and 

 psychological phenomena. Kunze, Fechner's nephew and biographer, 

 goes so far as to say, " they were among the first to raise the study 

 of nature among Germans to the eminence occupied by the philosophers 

 and discoveries of the Latin races." 9 Their first joint research is 

 typical of this. In the " Wellenslehre auf Experimente begrundet " 

 they add to Chladni's acoustic theory a parallel account for light, which 

 leads substantially to the inference of an elastic ether. Prior to this 

 Weber had published researches on the " Comparative Anatomy of the 

 Sympathetic Nerves" (1817) and " On the Ear and Hearing in Men 

 and Animals" (1827). His psychological contributions appeared in 

 Wagner's " Handworterbuch der Physiologie," Vol. III., part 2 (1831), 

 and in the " Archiv fiir anatomische Physiologie" (1835). The 

 classical paper, " Tastsinn und Gemeingefiihl," was printed in the 

 former and published separately in 1851. Weber here applied the 

 method of least observable differences to sensations of pressure and to 

 the measurement of lines by the eye. These experiments resulted in 



' " Physiol. Optik.," Helmholtz, p. 249. 

 8 Cf . Mind, V., pp. 1 ff. (old series). 



9 "Gustav Theodor Fechner (Dr. Mises) : Ein deutsches Grelehrtenleben," 

 243. 



