INTRODUCTORY. l65 



thesis, and because the only argument hitherto advanced 

 against it does not depend upon experiment, but on the 

 supposition that to admit its truth is to deny the existence 

 of an ascent in the scale of created beings. 



The object, therefore, of the present Essay is to show 

 in a general but very rapid manner, that the phasnomena 

 Vi^hich have been already recorded by learned anatomists 

 and naturalists are sufficient to give us a distant view of 

 a system which will embrace the whole of nature; — that 

 this system, though apparently complicated, is possessed 

 in all probability of a symmetry and unity superior to any 

 thing we can conceive, on considering the variety with 

 which they are combined ; — that the most beautiful ana- 

 logies become conspicuous even on the very slight glimpse 

 which I am able to give of it; — and finally, that so far is 

 this plan from militating against the doctrines of revealed 

 religion, that it will be found to depend on these as some 

 of its very best supports. 



It must be evident, however, that it is almost im- 

 possible to be free from error in an investigation like the 

 present, which embraces a general view of so vast a re- 

 gion as that of Zoology, the limits of which have al- 

 ways appeared more distant, more immeasurable, as the 

 examination of them has become more profound. No pub- 

 lication on Natural History has ever yet appeared unas- 

 sailable to criticism, and on the other hand, there are very 

 few indeed which have not some merit to claim. It ought 

 not however to be suspected that the labours of naturalists 

 have been useless in proportion to their inaccuracy, or 

 that theories have been injurious to the degree that they 

 may have been false. So much the reverse of this has been 

 the case, that science has gained as much by attempts to 



