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of the grand instinct of self-preservation ; and we could not 
deprive him of one of these without depriving him of his 
existence. 
Instinct being necessary to, and consequently inseparable 
from, animal existence, man possesses it in common with the 
lower animals. In addition to instinct, man also possesses 
what are termed the intellectual faculties. 
One of the chief objections which have been urged against 
the theory that intellect forms a distinctive characteristic of 
humanity, seems to be founded on the difficulty of compre- 
hending its various manifestations within the limits of a single 
word. Generally speaking, the question “ what is intellect V ’ 
is' nothing more or less than a challenge to solve this philo- 
logical problem. The ground has been gone over so often, 
that it is impossible to make fresh discoveries, and the man 
who attempts to frame an exhaustive definition of intellect 
merely expresses his adherence to the view of a particular 
metaphysician who has preceded him. Does it depend on 
the power of reflection? or of comparison? or of forming 
abstract ideas ? or is it simply an independent will acting 
upon highly developed animal faculties? We may accept 
either of these definitions singly, or we may accept them all, 
as describing different phases of the same quality, or we may, 
on the other hand, confess ourselves unable to form a clear 
conception of the essential nature of the intellect; but we 
know quite enough about it to be able to define it negatively 
as regards the psychology of the lower animals, just as a 
geologist may be unable to describe the nature and properties 
of a given rock, and yet may be perfectly certain that it is 
not granite. We know that, whatever intellect is } it is not a 
higher development of those instinctive feelings which are 
common to man and brute ; for the passions of man are not 
different in their nature, nor at all superior, to those of brutes ; 
while even the^advocates of the psychological identity of man 
and the lower animals allow the immense superiority of man 
intellectually ; and if human intellect and human feeling 
were different developments of the same quality, there would 
be intermediate degrees, and the two principles would never 
be in antagonism to each other. 
Nor does there seem to be any good reason for supposing that 
the intellect is identical in kind with the natural sagacity of 
animals. Whether animals possess this natural sagacity in 
addition to the instinct is not an easy question to answer, at 
least with any amount of certainty; but I think that sensa- 
tion and memory will account for all the phenomena of animal 
actions. An animal endeavouring to escape from an enemy, 
