THE DOGMA OF EVOLUTION 



Aristotle had criticised the earlier natural philoso- 

 phers in that they had confused substance and action, 

 and to avoid this confusion of thought he supposes 

 that the four elements may change from one to an- 

 other by the inherent active principles of moist and 

 dry, warm and cold. Thus earth which is cold and 

 wet becomes water if it be made warm and wet. By 

 an apparent contradiction, he also defines motion as 

 the active principle which produces form and change 

 of form. But this contradiction is cleared by his defi- 

 nition of motion as meaning any change in quantity, 

 in quality, or in space position; thus, the active prin- 

 ciples fall in the second category of motion, the size 

 of the body in the first, and its position in the third 

 category.^^ 



We may sum up Aristotle's postulates as four prin- 

 ciples — substance as potential, form as actual, the 

 moving cause which changes potential matter into 

 actual bodies, and the final, or end cause, which ex- 

 plains the reason for creation. Over all, regulating 

 and dominating all things, is God, an immaterial 

 spirit. To Aristotle, God is a necessary postulate be- 

 cause wherever he looks he sees design and order. 



13 It is interesting to note that although we now define motion as 

 being solely change of position in time, yet we still adhere to 

 Aristotle's three categories. For example; we explain colour as 

 vibratory motion of particles although there is no sense connection 

 in our minds between colour and position. When a body changes 

 its quality from red to green we explain it as due to motion. Many 

 chemists explain the difference between any two elementary sub- 

 stances, as hydrogen and oxygen, as merely a change of position of 

 electrons in the atom, etc. 



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