16 
INTRODUCTION. 
directed towards the accomplishing of adaptive movement, 
antecedent to individual experience, without necessary 
knowledge of the relation between the means employed 
and the ends attained, but similarly performed under the 
same appropriate circumstances by all the individuals of 
the same species. Now in every one of these respects, 
with the exception of containing a mental constituent and 
in being concerned in adaptive action, instinct differs from 
reason. For reason, besides involving a mental con- 
stituent, and besides being concerned in adaptive action, 
is always subsequent to individual experience, never acts 
but upon a definite and often laboriously acquired know- 
ledge of the relation between means and ends, and is very 
far from being always similarly performed under the same 
appropriate circumstances by all the individuals of the 
same species. 
Thus the distinction between instinct and reason is 
both more definite and more manifold than is that between 
instinct and reflex action. Nevertheless, in particular 
cases there is as much difficulty in classifying certain 
actions as instinctive or rational, as there is in cases where 
the question lies between instinct and reflex action. And 
the explanation of this is, as already observed, that instinct 
passes into reason by imperceptible degrees; so that 
actions in the main instinctive are very commonly 
tempered with what Pierre Huber calls 6 a little dose of 
judgment or reason,’ and vice versa . But here, again, the 
difficulty which attaches to the classification of particular 
actions has no reference to the validity of the distinctions 
between the two classes of actions ; these are definite and 
precise, whatever difficulty there may be in applying them 
to particular cases. 
Another point of difference between instinct and 
reason may be noticed which, although not of invariable, 
is of very general applicability. It will have been 
observed, from what has already been said, that the 
essential respect in which instinct differs from reason con- 
sists in the amount of conscious deliberation wdiich the 
two processes respectively involve. Instinctive actions are 
actions which, owing to their frequent repetition, become 
