THE AIM AND ACHIEVEMENTS OF SCIENTIFIC METHOD. 93 



compound " thing " which displays many of the properties of 

 the genuine " things " of common sense. Thus the perception 

 of a certain deflection of a galvanometer needle may be 

 regarded as the perception of a certain " current," just as, when 

 a certain noise falls upon a man's ear, he asserts that he 

 " hears " a hansom cah.* 



37. 



We have now reached, perhaps, a point from which we 

 obtain a clearer view of the circumstances under which, in the 

 history of Science, psychical events came to be excluded from 

 the causal series. To suppose that they are legally banished 

 under the terms of Hume's famous edict against investigations 

 that do not " contain any experimental reasoning concerning 

 matter of fact and existence," is a view that no one could hold 

 " except to save a theory."f And if they suffer through the 

 condemnation pronounced against inquiries that do not 

 "contain any abstract reasoning concerning quantity or 

 number" we see that this defect is not essential to their 

 nature as events, for "series" prevail in the psychical as 

 widely as in the physical world. The difficulty is reduced to 

 the practical difficulty of establishing for the terms of these 

 series (which, as I have pointed out in the first chapter, are 

 regarded as being " the same for all ") an unambiguous 

 correlation with the terms of the equally Objective number 

 series which happens, like much of the physical, to be not only 

 the same for all, but also accessible to all. ) Were such a cor- I 

 relation established it would apparently be possible to 

 determine whether certain psychical changes and physical 

 changes are or are not complete expressions of the " notice " 

 which soul takes of body or body of soul. 



* Cf. Poincare, La Valeur de la Science, p. 227. 

 t Bradley, Appearance and Reality ', p. 324. 



