APPENDIX I 

 A METAPHYSICAL DISCUSSION 



The argument of Chapter X. may be summarised as follows : 



" Sensation" is a purely physical process, beginning with the 

 stimulation of a sense organ and ending with the physical affec- 

 tion of a nerve centre. In it are involved only molecular dis- 

 placements of the substance of nerve fibres and cells. It is not 

 accompanied by changes in consciousness. 



" Pure perception " is the prolongation of this physical process 

 of sensation into appropriate actions. Beginning in the animal 

 body with the stimulation of a sensory organ, it ends with a 

 motor action (that is, the co-ordinated movements of a system 

 of muscles), or a glandular change (that is, a process of secretion, 

 or other form of metabolism). It is unaccompanied by any 

 change of consciousness when it is " pure." That is, of course, 

 a limiting case exemplified by typical reflexes, most habitual, 

 visceral responses (respiration, the heart -beat, peristalsis, 

 " mechanical," " habitual," " automatic," and instinctive re- 

 sponses). In such cases consciousness may be absent or very dim. 



" Perception " simply means a chosen response — one that is 

 ^ accompanied by some degree of deliberation, and exhibits some 

 degree of freedom or novelty. We are compelled to postulate 

 this indeterminism of response in admitting the continued evolu- 

 tion of form and functioning, and we are convinced of it if we 

 reflect upon our conduct and the motives that sway us. Such 

 deliberated, chosen, and free response is again the limiting case, 

 because habit; physical, legal, and moral restraints; heredity 

 and convention, determine largely what we shall do in any 

 circumstances. But not altogether. There is some degree of 

 true freedom of acting. 



The greater the degree of indeterminism that follows upon a 

 sensation, so much greater is the pitch of consciousness. In 

 strong and sustained mental effort there is just this intensely felt 

 deliberation. The latter may end in a choice (when we take 

 some course of action), or it may end in a solution (as when one 

 works out some physical or mathematical problem) — ^that is, it 

 ends in an actual or virtual action. Then one feels the strongest 

 possible mental satisfaction. 



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