56 INTRODUCTION. 



but the expression of their momentary sensations, 

 but still they can learn from man some degree of 

 knowledge of his much more complex and artificial 

 language, through the medium of which he makes 

 his commands known to them, and determines their 

 execution. 



In short, we perceive in the superior animals a 

 certain degree of reason, with the consequences, 

 both good and bad, resulting from the exercise of 

 that faculty in man. It resembles the dawning of 

 intellect in the infant mind previously to the ac- 

 quirement of speech. In proportion as we descend 

 in our observations to animals more and more re- 

 mote from man, we find a corresponding diminution 

 of intellectual power, till in the lowest classes we 

 can only recognise a few equivocal signs of the 

 existence of mere sensibility, or, to speak more de- 

 finitely, certain languid motions, which they appear 

 to employ for the purpose of escaping from pain 

 The gradations, however, between the two extremes 

 of the animal world are innumerable. 



In a great number of animals there also exists a 

 faculty essentially different from any thing like hu- 

 man intelligence, denominated instinct. This faculty 

 impels them to the performance of certain actions 

 necessary to the preservation of the species, but 

 frequently altogether foreign to the apparent wants 

 of the individual. The operations of this faculty are 

 often extremely complicated, and discover a fore- 

 sight, skill, and knowledge so infinitely beyond what 



