ON THE PSYCHO-PflYSICAL VIEW OF XATFRE. 401 



these Heliiilioltz is led into lesthetical and psycholofrical 

 discussions, clearly distinguishing between such principles 

 as are inherent in natural, physical, and physi(jlogical 

 relations, and such others as depend on the inventions of 

 genius and the gradual changes l)rought aljout by exter- 

 nal requirements and ingrained by habit and education.^ 

 The physiology of seeing had yet more remarkable 

 consequences for the history of Thought. We may say 

 that through Helmholtz's analysis of the formation of 

 our space perceptions by the eye in connection with the 

 tactile and muscular senses, psychology and metaphysics 

 were brought into immediate contact with physics and 

 physiology. It is here that Helniholtz takes up an ir. 



i.-iT/'P ±^ 1 • 1.1 1 Helmholtz 



entirely ditJerent, and, previously, isolated line of reason- a"d Kant, 

 ing, which centres in Kant's theory of space and time as 

 innate forms of perception — the so-called subjectivity or 

 ideality of time and space. The studies of this subject" 

 had been somewhat prepared by the writings of Herbart 

 and Lotze. The teachings of Kant have had an influence 

 in the direction indicated through two distinct channels, 

 — through Johannes Midler's rhvsiology and through 

 Herbart's Psychology : the latter seems to have had 



^ See the closing words of the 

 13th chapter of Helmholtz's work : 

 " As the fundaracntal j)riiici|)le for 

 tlie developeiiieiit of the European 

 tonal system, we shall assume that 

 tlie whole mass of tones and the 

 connection of harmonics must stand 

 in a close and always distinctly 

 perceptible relationship to some 

 arbitrarily selected tonic, and that 

 the mass of tone which forms tlie 

 whole composition must be de- 

 veloped fi-om this tonic, and must 

 finally return to it. The ancient 

 world dcvelojicd this pirinciple in 



homophonic music, the modern 

 world in harmonic music. But it 

 is evident that this is merely an 

 icsthetical princi])lc, not a natural 

 law. The correctness of this juin- 

 ciple cannot be established a priori. 

 It must be tested by its results. 

 The origin of such wsthetical i)rin- 

 ciples should not be ascribed to a 

 natural necessity. They are the 

 inventions of genius, as we pre- 

 viously endeavoured to illustrate 

 by a reference to the principles of 

 arcliitectural style." 



