A HISTORY OF SCIENCE 



throw of the last Roman Empire of the West, might 

 seem to indicate. But, on the other hand, no student 

 of the period can fail to realize that a great change 

 came over the aspect of the historical stream towards 

 the close of the Roman epoch. 



The span from Thales to Galen has compassed about 

 eight hundred years let us say thirty generations. 

 Throughout this period there is scarcely a generation 

 that has not produced great scientific thinkers men 

 who have put their mark upon the progress of civiliza- 

 tion; but we shall see, as we look forward for a cor- 

 responding period, that the ensuing thirty generations 

 produced scarcely a single scientific thinker of the 

 first rank. Eight hundred years of intellectual ac- 

 tivity thirty generations of greatness; then eight 

 hundred years of stasis thirty generations of medioc- 

 rity; such seems to be the record as viewed in per- 

 spective. Doubtless it seemed far different to the 

 contemporary observer; it is only in reasonable per- 

 spective that any scene can be viewed fairly. But for 

 us, looking back without prejudice across the stage of 

 years, it seems indisputable that a great epoch came 

 to a close at about the time when the barbarian 

 nations of Europe began to sweep down into Greece 

 and Italy. We are forced to feel that we have reached 

 the limits of progress of what historians are pleased to 

 call the ancient world. For about eight hundred years 

 Greek thought has been dominant, but in the ensuing 

 period it is to play a quite subordinate part, except 

 in so far as it influences the thought of an alien race. 

 As we leave this classical epoch, then, we may well 

 recapitulate in brief its triumphs. A few words will 



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