52 INTRODUCTION. 



once condescend to study the coiTesponding parts 

 and actions of quadrupeds, and how vast would be 

 the increase, by the numberless associations thus 

 opened to him, of his knowledge, with respect to 

 things which he had previously perhaps imagined 

 he had perfectly understood ! Again, let him 

 descend to birds and reptiles, and at each step of 

 his progress, his acquaintance, not only with the 

 subjects immediately in hand, but with every thing 

 appertaining to the subjects of his previous studies, 

 will be increased almost infinitely ; — new and un- 

 thought of relations spring up at every turn ; — 

 aaalogies, numerous and striking in proportion to 

 the greater extent of his grasp, every where meet 

 him ; — and facts which he at first acquiesced in as 

 ultimate, and knew only as disjointed links of a 

 chain, of the extent and complication of which he 

 was profoundly ignorant, he now contemplates as 

 parts of a stupendous whole, and is at once de- 

 lighted and exalted by the contemplation. But 

 the goal is only in view; it is not yet attained. 

 Let him proceed to Fishes, or to those animals 

 destitute of a skeleton, and further light still 

 breaks in upon him; he finds, in the study of 

 their economy, many of his former blanks filled 

 up — many of his former en-ors corrected — many 

 difficulties removed — many just conclusions esta- 

 blished or corroborated — many happy associations 

 illustrated or extended. It may be received as 

 an axiom, that the less a man knows, not only the 

 less susceptible is he of further knowledge, but 



