THE GREEK ATTITUDE 



Without it we lose all sense of identity and the his- 

 tory of an object is impossible if the material of it 

 may disappear or reappear. No chemist can do more 

 than find a rough approximation of quantities of mat- 

 ter with his balance. And even if he could attain abso- 

 lute accuracy, the generalization would still remain 

 a pure deduction because it must include the matter of 

 the sun and stars which is absolutely outside our de- 

 termination by measurement. The same arguments 

 apply to the law of conservation of energy. Both of 

 these ideas were recognized and stated accurately by 

 Democritus. The third scientific postulate is the law 

 of cause and effect which was best formulated by 

 Aristotle. While the bearing of these three on biology 

 is readily seen, the fourth postulate of continuity of 

 all actions in time is perhaps the most directly ap- 

 plicable to evolution. This concept, which in physics 

 is assumed to be true of all mechanical motions, takes 

 the form in biology of variation as the origin of 

 species instead of special creation. The significance 

 of continuity in both space and time in organic phe- 

 nomena was never fully appreciated by the Greeks; 

 the clearest formulation by them of it is due to Aris- 

 totle and may be stated : Every organic form has a 

 parent not only in idea but also in time, and there is 

 variation within any species which the soul {psuche) 

 of the individual effects. 



These deductive laws are the real achievement of 

 the Greeks in science. By themselves they are not suf- 



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