PREFACE. 



The distinctions between Reason and Instinct 

 are difficult to ascertain : to define their exact 

 limits has exercised the ingenuity of the most 

 profound philosophers, hitherto, without success. 

 Nor can the learned agree as to the nature of that 

 wonderful quality, that guides every creature to 

 take the best means of procuring its own enjoy- 

 ment, and of preserving its species by the most 

 admirable care of its progeny. Some degrade 

 this hidden impulse to a mere mechanical opera- 

 tion ; whilst others exalt it to a level with reason, 

 that proud prerogative of man. There are, in- 

 deed, innumerable gradations of intelligence, as of 

 the other qualities with which the animal king- 

 dom is endowed ; in like manner as the different 

 orders of beings approach each other so closely, 

 and are so curiously united by links, partaking of 

 the nature of those above and those below, that 



