COSMIC PHILOSOPHY 



the visual perception of a peach, answering in 

 some way to the objective relation between the 

 coexistent properties of the peach, so that the 

 presentation of the one to the cephalic ganglia 

 is inevitably accompanied by the representation 

 of the other ? This question lies at the bottom 

 of psychology, and we have now to see how it 

 is to be answered. The answer will lead us 

 through a portion of the domain of molecular 

 physics, and will incidentally give us a hint con- 

 cerning the genesis of nervous systems. 



In the chapter on Matter, Motion, and Force, 

 it was shown that all motion takes place along 

 the line of least resistance, whether the motion 

 be the movement of a mass of matter through 

 a resisting medium, or the passage of a series 

 of undulations through the molecules of an ag- 

 gregate. Let us reconsider this truth in one of 

 its concrete applications. 



When a wave of molecular motion traverses a 

 mass of matter for the first time, the line of least 

 resistance will of course be determined by the 

 intimate structure of the mass. But now mark 

 what happens. Immediately after the passage 

 of the wave, the intimate structure of the mass, 

 in the vicinity of the line along which the wave 

 has travelled, is different from what it was a 

 moment ago. The passage of the wave has 

 pushed a linear series of molecules out of posi- 

 tion, and a short time must elapse before these 

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