SOURCES OF THE NEW PSYCHOLOGY. 103 



It is to be noted that these statements refer to investigations 

 of and speculations on the brain for psychological purposes. For 

 physiological purposes the case is utterly different. The develop- 

 ment of brain anatomy and of the knowledge concerning the 

 localization of cerebral functions are among the greatest achieve- 

 ments of modern times.* 



Moreover, the collection of facts and the development of 

 theories of the nervous activities accompanying mental phe- 

 nomena has given rise to the science of physiological psychology.! 



With these sciences, however, the psychologist has compara- 

 tively little to do. The study of brain function has not con- 

 tributed a single fact to our knowledge of mental life ; the deduc- 

 tions of physiological psychology concerning nervous function 

 have begun with the facts of experimental and observational 

 psychology, and are still so unsettled as not to allow additional 

 deductions backward. 



While this was going on, physics had through Helmholtz, J 

 Mach,* and others gradually come to a clear understanding of 

 the relation of its facts to the immediate facts of consciousness. 

 Direct experience as present in our sensations was accepted as 

 supplying the facts of physics. For example, in measuring the 

 length of a bar, a visual sensation, the scale of measurement, was 

 applied to another visual sensation, the bar. Indeed, as was 

 clearly recognized, every direct measurement of physics was 

 primarily a comparison between sensations in other words, a 

 psychological measurement. From this combined measurement 

 the physicist reduced as much as possible the psychological ele- 

 ments ; it was but a step for the psychologist to reduce the phys- 

 ical elements in order to have a psychological measurement. || 

 This step made psychology for the first time a science in the 



* For a historical sketch and an account of the latest remarkable discovery, see Flechsig, 

 Gehirn und Seele, Leipzig, 1896. 



f As a representative work see Exner, Entwurf zu einer physiologischen Erklarung der 

 psychischeu Erscheinungen, i. Theil, Lepzig, 1894. For a convenient summary see Ziehen, 

 Leitfaden der physiologischen Psychologic, second edition, 1893, also translated. 



^ Helmholtz, Ueber das Ziel und die Fortschritte der Naturwissenschaft, Populare wiss. 

 Vortrage, Braunschweig, 1871. Helmholtz, Die Thatsachen in der Wahrnehmung, Leipzig, 

 1879. 



* Mach, Die Mechanik in ihrer Entwickelung, Leipzig, 1883, second edition, 1889; also 

 translated into English, Chicago, 1895 (Mach's earlier monographs are mentioned in the 

 preface). Mach, Beitrage zur Analyse der Empfindungen, p. 141, Jena, 1886. 



I The psychological standpoint has been clearly stated by Wundt, Ueber die Messungen 

 psychischer Vorgange, Philos. Studien, 1883, vol. iv, p. 1 ; Weitere Bemerkungen iiber psy- 

 chische Messungen, Philos. Studien, p. 463 ; Ueber die Entheilung der Wissenschaften, 

 Philos. Studien, 1889, vol. v, p. 1 ; Ueber die Definition der Psychologic, Philos. Studien, 

 1896, vol. xii, p. 1 ; Ueber naiven und kritischen Realismus, Philos. Studien, 1896, vol. xii, 

 p. 307. I have followed Wundt in The Problem of Psychology, Mind, 1891, vol. xvi, p. 

 305 ; Psychological Measurements, Philosophical Review, 1893, vol. ii, p. 677. 



