SCIENCE AND PHILOSOPHY 



law indicated the interrelation and common 

 descent of all plants from one primeval type. 

 And in his " Metamorphosis of Animals," he 

 made the same claims in regard to the origin of 

 animals. This was but a return of the human 

 mind, after a long and fruitless drift around a 

 circle, to the ideas of the Grecian natural philos- 

 ophers. But now the facts for an empirical proof 

 of this theory were within reach, and were soon 

 to be marshalled against the Mosaic theories, 

 which had dominated the human mind since the 

 advent of the medieval church to power. 



In 1809, Lamarck came forth with his " Philos- 

 ophie Zoologique " and developed the theory of 

 natural evolution systematically. He struck first 

 of all a crushing blow at the metaphysical con- 

 ception of the mysterious nature of life, which the 

 naturalists of the i8th century had attributed to 

 a supernatural vital force. He opposed this idea 

 of vitalism by the theory that the primeval an- 

 cestors of living beings on this globe were the 

 simplest organisms imaginable and were gener- 

 ated spontaneously by the interaction of physical 

 causes, as soon as the globe had cooled sufficiently. 

 Half a century later, such simple organisms were 

 actually discovered, and still fifty years later the 



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