SURVEYS OF NATURE. 9 



confiderable. (6) They feem capable of uniting their varieties 

 more than quadrupeds are. (7) With regard to fome of them, 

 though we can delcribe their manners while with us; we know 

 little of their procedures while abfent : in (hort, birds more ea- 

 {ily efcape our purfuit than quadrupeds ; and confequently our 

 knowledge is built on more diftant acquaintance. 



Thus circumftanced, muft we give up the purfuit of knowledge, 

 or be content with what is attainable? Certainly, thefe obftacles 

 may excite diligence in the obferver, and candour in the inftrud;- 

 ed; for evidently much remains obfcure, and equally evidently, 

 what is difcovered has been the work of time, and the effedt 

 of labour, toil, trouble, expence, dexterity, genius, and remark, 

 which though they may err, yet on the whole deferve praife ; 

 and though not complete in knowledge, may juftly afllimc 

 a credit for all that is known. 



