Reason and Instinct, 



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know, and by analogy, to what we do not know ; and certainly it 

 is conceivable that our conclusions may be wrong. 



But I am sure of this, that whether or no we are wrong in denying 

 the presence, at least, the operation of Instinct in all these creatures, 

 the Instinct of those creatures in which the presence and influence 

 of that Power is only just displayed is very different in power or 

 degree (probably not the least so in nature), and in results, from that 

 of the alligator, the salmon, the swallow or the rabbit. In the one 

 case, it is a stream flowing on to its outlet, but a stream of small 

 volume and inconsiderable motion ; and one or two small mouths are 

 sufficient for its debouchure. In the other case, — that of the higher 

 animals, — on the contrary, the stream is of greater — it may be, vastly 

 greater — volume and velocity; and it rushes on to the ocean of 

 Actioi> through many and various and considerable branches and 

 outlets. 



I think that this is an important consideration: — that Instinct — 

 assuming that Power or Attribute or Essence to be the same in all 

 cases ; viz., a " determination to act, given by Almighty Wisdom" — 

 acts with different degrees of intensity, as estimated by its collective 

 results, in the different orders of creatures whose conduct is per- 

 ceptibly influenced by it. I mean, that in some — at the lower end, 

 so to speak, of an ascending scale — the operation or influence of un- 

 questionable Instinct is only just recognisable with sufficient dis- 

 tinctness ; in others near the other end of the scale it is very strong 

 and influential indeed ; and that between these extremes every inter- 

 mediate modification of power and energy in its action may be met 

 with. That this observation is well-founded, I think scarcely any one 

 will be disposed to deny who compares the instinctive actions, — say 

 of an earthworm, a snail or a caterpillar with those of a wild duck, a 

 dog or a monkey, — and then bears in mind the list of heads, confessedly 

 imperfect, under which the instinctive actions of animals must be 

 arranged, and how remarkably, as we descend the scale of animated 

 life, the decrease of evidences of instinctive action, in its strongest 

 forms, keeps pace with the descent. It would not be difficult to illus- 

 trate this point by successive comparisons of the instinctive tendencies 

 and performances, taken separately and collectively, of a reptile with 

 those of a fish, a bird, and a quadruped belonging to one of not the 

 highest classes : and we shall adduce something of the sort a little 

 further on. 



And with a view to obviating the difficulty suggested above, I would 

 observe that the successive comparisons just named will probably lead 



