CHAPTER IV 



THE END OF N A T U R A L - P H I LO SO P H I C A L SPECULATION. THE 

 PREDECESSORS OF ARISTOTLE 



The results of natural philosophy 

 A N ENTIRE ERA in the history of biology closes with the philosophers 

 / \ that have here just been characterized — Democritus, Hippocrates, 

 JL JL and his school — an era which may properly be called the era of 

 natural-philosophical speculation. The results achieved by their researches 

 cannot be regarded as anything but magnificent; for the first time in the his- 

 tory of humanity to have built up a real natural science is an achievement 

 worthy of the highest admiration, however modest the results may have been 

 in certain details. This research work had so far been directed by three illus- 

 trious representatives, Anaximander, Empedocles, and Democritus. All of 

 them sought an explanation of existence as a natural course of events; in 

 this direction Democritus proceeded as far as human thought has at any 

 period proved capable of going. Nevertheless, even in his own lifetime the 

 revolution was being prepared which was shortly to lead Greek thought in 

 entirely different directions. The first ideas on which this change was based 

 originated, as hinted above, from the school of the Sophists. The new prin- 

 ciple that they taught was subjectivity: "Man is the measure of all things. " 

 To this really true assertion the ancient "physicists" could make no objec- 

 tion; indeed, their cosmic explanations were as numerous as themselves, 

 and each one of them could only declare dogmatically that his own views 

 were the true ones and thereupon produce a number of more or less illogical 

 arguments in support of them. The claim of the Sophists as to man's being 

 the measure of all things thus for the time did away with all objective ex- 

 planations of natural phenomena, for what was the use of disputing about 

 matters which all viewed from different standpoints if all could be equally 

 right? Sophistry itself, however, when consistently applied, led to pure 

 nihilism, both intellectual, in that the object was, by means of ingenious 

 turns of phrase ("sophisms"), to prove absolutely anything, and moral, 

 in that all generally accepted sound traditions were held in contempt as 

 laying a restraint upon the individual's freedom of action. If all scientific 

 thought were not to be destroyed altogether, its preservation must be sought 

 by turning the whole trend of thinking into quite a different direction. And 

 this was found by maintaining that human thought, however much it may 



3° 



