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or a Ptolemy. In efFed paft geological fads being of an hiftorical 

 nature, all attempts to deduce a complete knowledge of them 

 merely from their flill fubfifting confequences, to the exclufion of 

 unexceptionable teftimony, muft be deemed as abfurd as that of 

 deducing the hiftory of ancient Rome folely from the medals or 

 other monuments of antiquity it fliil exhibits, or the fcattered 

 ruins of its empire, to the exclufion of a Livy, a Sallufl or a 

 Tacitus. That great changes have taken place on the furface of 

 the globe fince the commencement of its exiftence, changes that 

 for fome thoufand years have not been repeated, is allowed on all 

 hands. What then fhould render thefe fads and the circum- 

 ftances attending them unfufceptible of teftimony ? not furely 

 their improbability or difcrepance with adual obfervation, fince 

 their reality is confeflTed by all ; with refped to fome of them 

 I can think of no reafon but one, and that indeed at the firft blufh 

 fufficiently plaufible, namely that their exiftence preceded that of 

 the human fpecies; this certainly proves that the knowledge of 

 the hiftorian that relates them (fuppofing him to have any) was 

 not as to fuch fads obtained by human means. But if in a fe- 

 ries of fads difcovered by an inveft:igation to which the witnefs 

 was an utter ftranger, an exad agreement with the relation of 

 the hiftorian be difcerned, not barely as to the fubftancc of the 

 fads but even as to the order and fucceffion of their ex- 

 iftence, in fuch cafe it muft be acknowledged that the rela- 

 tion is true, let the knowledge of the hiftorian have been ob- 

 tained 



