518 SCIENTIFIC THOUGHT. 



looked upon as concomitant occurrences, as " Begleit- 

 erscheinungen " or " Epi-phenomena " of the more ac- 

 cessible though very complex phenomena of the nervous 

 system and its centres ; whereby it had to be noted, 

 that whilst the external visible processes exhibit that 

 continuity in time and space which is characteristic of 

 all physical phenomena, the epi-phenomena were subject 

 to discontinuous appearance and disappearance, to sudden 

 growth and collapse. Having got hold of this partial 

 formula, which in some cases admits even of a rigorous 

 mathematical expression, psycho-physics had no pressing 

 need of investigating its meaning any further, or of in- 

 quiring into the supposed independent existence or signif- 

 icance of the " epi-phenomena " as such ; similar general 

 inquiries into the origin of gravitation, of atoms, of the 

 essence of energy or inertia, having proved to be of little 

 or no use in furthering astronomy, chemistry, thermo- 

 dynamics. It cannot be denied that this is a perfectly 

 tenable scientific attitude. Such an attitude has notably 

 been taken up by Dr Hugo Munsterberg, and by what 

 we may term the Freiburg school of psycho -physics. 

 Also there is no doubt that through a series of very 

 cleverly contrived experiments particularly those re- 

 ferring to the muscular sense and the time sense a 

 good deal of light has been thrown upon such mental 

 processes as association of ideas, attention, apperception, 

 and voluntary effort, which have thus been brought 

 into closer correspondence with changes taking place in 

 35. the nervous system. In fact, a parallelism of neurosis 



Doctrine of 



parallelism, and of psychosis has been more and more established. 

 This doctrine of psycho - physical parallelism, also 



