FOSSIL ORGANISMS. 55 



creation/' the infallible and indisputable records wliicb fix 

 the correct history of organisms upon an irrefragable founda- 

 tion. All petrified or fossil remains and impressions tell us 

 of the forms and structure of such animals and plants as are 

 either the progenitors and ancestors of the present living 

 organisms, or they are the representatives of extinct colla- 

 teral lines, which, together with the present living organisms, 

 branched ofi" from a common stem. 



These inestimable records of the history of creation 

 throughout a long period played a subordinate part in 

 science. Their true nature was indeed correctly understood, 

 even more than five hundred years before Christ, by the 

 great Greek philosopher, Xenophanes of Colophon, the same 

 who founded the so-called Eleatic philosophy, and who was 

 the first to demonstrate with convincing precision that all 

 conceptions of personal gods result in more or less rude 

 anthropomorphism. 



Xenophanes for the first time asserted that the fossil im- 

 pressions of animals and plants were real remains of formerly 

 living creatures, and that the mountains in whose rocks 

 they were found must at an earlier date have stood under 

 water. But although other great philosophers of antiquity, 

 and among them Aristotle, also possessed this true know- 

 ledge, yet throughout the illiterate Middle Ages, and even 

 with some naturalists of the last century, the idea prevailed 

 that petrifactions were so-called freaks of nature (lusus 

 naturae), or products of an unknown formative power or 

 instinct of nature (nisus formativus, vis plastica). Respect- 

 ing the nature of this mysterious and mystic creative 

 power, the strangest ideas were formed. Some believed that 

 this constructive power — the same to which they also 



