249 PHILOSOPHY OF ZOOLOGY. 
powers, suffering no mtermediate modifications, produce 
actions characterised by great uniformity. 
In many cases, when an impression is produced upon us, 
which, as belonging to the instinctive powers, would have been 
followed by action, the intellectual powers interpose their 
controul!, and the impression is surveyed before action is per- 
mitted. But, as might have been expected, such action is 
less varied, than when originally the result of an imtellec- 
tual process, but more irregular than in those cases in 
which impression and action follow instantaneously. In 
the one case, the action is modified by the impression,—in 
the other, by the changes the impression has undergone by 
thought. 
The powers to which we are now directing our attention, 
are usually denominated, by the writers on the science of 
mind, activE rowers. ‘To this appellation, however, 
there are strong objections. There are other powers which 
excite to action, inseparably connected with our constitu- 
tion, which do not belong to this class. Some actions are 
produced by irritability, of which we are not conscious. Ac- 
tion is likewise produced by the information obtained by the 
‘senses, through the medium of thought,—or in consequence 
of the ideas of reflection which spontaneously arise in the 
mind. Hence the difference between the intellectual and in- 
stinctive powers, 1s not so distinctly marked in the acts of 
volition as in the manner in which these aets are exci_ed. 
It is with a view to avoid all ambiguity on the subject, that 
we have ventured to substitute the term instinctive. 
Much confusion has arisen by the vague use of the 
terms Instinct and Reason, and much vain- speculation has 
been indulged, in consequence of no distinct and definite 
ideas being attached to them. No confusion, however, 
could arise, were we to consider reason as expressing the 
movements of our Intellectual powers,—and_ instinct, those 
