INSTINCT OF INSECTS. 465 



it lias never tasted milk, the infant* seeks for its mo- 

 ther's breast, is the effect of reason. 



Instinct, then, is not the result of a plastic nature ; of 

 a system of machinery ; of diseased bodily action ; of 

 models impressed on the brain; 'nor of organic shoot- 

 ings-out : it is not the effect of the habitual determina- 

 tion for ages of the nervous fluid to certain organs; nor 

 is it either the impulse of the Deity, or reason. Without 

 pretending to give a logical definition of it, which while 

 we are ignorant of the essence of reason is impossible, 

 we may call the instincts of animals those unknown fa- 

 culties implanted in their constitution by the Creator, 

 by which, independent of instruction, observation, or 

 experience, and without a knowledge of the end in view, 

 they are impelled to the performance of certain actions 

 tending to the well-being of the individual and the pre- 

 servation of the species : and with this description, 

 which is in fact merely a confession of ignorance, we 

 must, in the present state of metaphysical science, con- 

 tent ourselves. 



I here say nothing of that supposed connexion of the 

 instinct of animals with their sensations, which has been 

 introduced into many definitions of this mysterious power, 

 for two reasons. In the first place, this definition merely 

 sets the world upon the tortoise ; for what do we know 

 more than before about the nature of instinct, when we 

 have called it, with Brown, a predisposition to certain 

 actions when certain sensations exist, or with Tucker 

 have ascribed it to the operation of the senses, or to that 

 internal feeling called appetite ? But, secondly, this 

 connexion of instinct with bodily sensation, though pro- 

 bable enough in some instances, is by no means gene- 



VOL. II. 2 H 



