An Introduction to a Biology 



The part played by words, however, in deter- 

 mining the course of human thought is a minor 

 though by no means a negligible one ; but that 

 which has chiefly directed its course is the set of 

 habits with which the human mind began, and 

 especially those which it developed during its 

 acquisition of control over external matter. 



Let us see to what extent our modern conception 

 of the organism and our theory of the evolution of 

 life are what the early schooling of the mind would 

 lead us to expect them to be. 



To deal first with the organism. It was well- 

 nigh inevitable that the human mind, in casting 

 about for a conception of the organism., for an 

 explanation of its activities, should light upon that 

 one of its offspring which, though not its firstborn, 

 was the apple of its eye — ^the machine. At any 

 rate, whatever else might have happened, this is 

 what has happened. Kene Descartes, the father 

 of physiology, the science whose function it is to 

 discover the causes of the activities of animals 

 (and plants too), was the author of the mechanistic 

 theory of the organism. The essence of this theory 

 is that a living thing does what it does because it 

 is made in the way it is made. The function of 

 an organ is determined by its structure. If we could 

 know everything about the structure of an organism, 

 we could predict how it would behave in response 

 to any imaginable set of stimuli. The analogy used 

 by Descartes to illustrate his theory of the organism 

 is well known. He compared the human body to 

 one of those grottos, devised for the amusement 

 of princes, in which there were waterfalls and foun- 

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