CAUSE AND EFFECT— PROBABILITY 119 



their will of originating " motion," In this manner we find 

 that most primitive peoples attribute all motions to some 

 will behind the moving body ; for their first conception of 

 the cause of motion lies in their own will. Thus they 

 consider the sun as carried round by a sun-god, the moon 

 by a moon-god, while rivers flow, trees grow, and winds 

 blow owing to the will of the various spirits which dwell 

 within them. It is only in the long course of ages that 

 mankind more or less clearly recognises will as associated 

 with consciousness and a definite physiological structure ; 

 then the spiritualistic explanation of motion is gradually 

 displaced by the scientific description ; we eliminate in 

 one case after another the direct action of will in the 

 motion of natural bodies/ The idea, however, of enforce- 

 ment, of some necessity in the order of a sequence remains 

 deeply rooted in. men's minds, as a fossil from the 

 spiritualistic explanation which sees in will the cause 

 of motion. This idea is unfortunately preserved in 

 association with the scientific description of motion, and 

 in the materialist's notion of force as that which }icces- 

 sitates certain changes or sequences of motion, we have 

 the ghost of the old spiritualism. The force of the 

 materialist is the will of the old spiritualist separated 

 from consciousness. Both carry us into the region 

 beyond our sense-impressions, both are therefore meta- 

 physical ; but perhaps the inference of the old spiritualist 

 was, if illegitimate, less absurdly so than that of the 

 modern materialist, for the spiritualist did not infer will to 

 exist beyond the sphere of consciousness with which he 

 had always found will associated. 



Force as cause of motion ^' is exactly on the same footing 

 as a tree-god as cause of growth — both are but names 

 which hide our ignorance of the zvhy ini the routine of our per- 



^ The spiritualistic explanation still of course exists where the scientific 

 analysis is incomplete. We continue to appeal to a spirit "at whose com- 

 mand the winds blow and lift up the waves of the sea and who stilleth the 

 waves thereof," or who "sends a plague of rain and waters." 



^ Force as a name used for a particular measure of motion will be found 

 in our chapter on the " Laws of Motion " to involve no obscurity, and to be 

 in itself a convenient term., • 



