ced that, either way, the causes
which arouse and provoke acts are sometimes internal and sometimes
external, that these same causes give rise in reality to impressions
all of which act internally.

"According to the idea generally attached to the word _instinct_ the
faculty which this word expresses is considered as a light which
illuminates and guides animals in their actions, and which is with
them what reason is to us. No one has shown that instinct can be a
force which calls into action; that this force acts effectively
without any participation of the will, and that it is constantly
directed by acquired inclinations."

There are, the author states, two kinds of causes which can arouse the
inner feeling (organic sense)--namely, those which depend on
intellectual acts, and those which, without arising from it, immediately
excite it and force it to direct its power of acting in the direction of
acquired inclinations.

"These are the only causes of this last kind, which constitute all
the acts of _instinct_; and as these acts are not the result of
deliberation, of choice, of judgment, the actions which arise from
them always satisfy, surely and without error, the wants felt and
the propensities arising from habits.

"Hence, _instinct_ in animals is an inclination which necessitates
that from sensations provoked while giving rise to wants the animal
is impelled to act without the participation of any thought or any
act of the will.

"This propensity owes to the organization what the habits have
modified in its favor, and it is excited by impressions and wants
which arouse the organic sense of the individual and put it in the
way of sending the nervous fluid in the direction which the
propensity in activity needs to the muscles to be placed in action.

"I have already said that the habit of exercising such an organ, or
such a part of the body, to satisfy the needs which often spring up,
should give to the subtile fluid which changes its place where is to
be operated the power which causes action so great a facility in
moving towards this organ, where it has been so often employed, that
this habit should in a way become inherent in the nature of the
individual, which is unable to change it.

"Moreover, the wants of animals possessing a nervous system being,
in each case, dependent on the Structure of these organisms, are:

"1. Of obtaining any