INTRODUCTION 



est book! The despair of the biographer has never 

 been more lucidly expressed than by St. John: "And 

 there are also many other things which Jesus did, the 

 which, if they should be written every one, I suppose 

 that even the world itself could not contain all the 

 books that should be written." 



There is an insidious temptation presented to the 

 writer of the natural history of prehistoric times to 

 construct a consistent outline of the changes in the 

 inorganic and in the organic world. He approaches 

 the subject, usually, with a belief in one or another 

 cause for evolution which has been elucidated from 

 experiments on the now existing forms of life. He 

 unconsciously emphasizes those facts which agree 

 with his theory, and this bias is the more harmful be- 

 cause the accumulation of exact knowledge in palae- 

 ontology is so slow that there is comparatively little 

 risk of definite discoveries being made which will en- 

 able the reader to check the errors or to see clearly the 

 bias. In this respect, he must remain far more un- 

 trustworthy, and consequently more dangerous, than 

 the narrator of human history. Thus, Macaulay, with 

 his bias towards the Whig theories of government, 

 could find in the archives of England only facts which 

 glorified Whig or dimmed Tory achievements. The 

 fascination of his style may sway the reader but, in 

 the end, he is able to regain his balance because the 

 records at his disposal are ample and, even if he does 

 not consult them for himself, he may learn their char- 



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