THE COMPOSITION OF MIND 



those forms of animal existence which possess 

 any nervous structure whatever. For instance, 

 that reflex action which occurs when the foot of 

 a sleeping person, casually moved into a cold 

 part of the bed, is quickly withdrawn without 

 arousing any state of consciousness, involves the 

 activity of a fragment of the human nervous 

 system which corresponds in general structure 

 to the entire nervous system of a medusa or 

 jelly-fish. In such lowly creatures, then, we 

 must suppose that the psychical actions which 

 go on are similar to our own sub-conscious psy- 

 chical actions. And, clearly, if we could trace 

 the slow increments by which the nervous sys- 

 tem has grown in heterogeneity, definiteness, 

 and coherence, during the countless ages which 

 have witnessed the progress from the primeval 

 marine vertebrate to the civilized modern man, 

 we should also be able to trace the myriad stages 

 of the composition of mind, from the reflex 

 contractions of a rudimentary fin, up to the 

 generalizations of an Aristotle or a Newton. 



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