330 LAMARCK, HIS LIFE AND WORK 
“T have already made it evident that this internal 
force which produces movements and actions should 
derive its origin in the intimate feeling of existence 
which animals with a nervous system possess, and 
that this feeling, solicited or aroused by needs, should 
then start into motion the subtile fluid contained in 
the nerves and carry it to the muscles which should 
act, this producing the actions which the needs 
require. 
“Moreover, every want felt produces an emotion 
in the inner feeling of the individual which ex- 
periences it; and from this emotion of the feeling 
in question arises the force which gives origin to 
the movement of the parts which are placed in ac- 
CAVA Mens 
“Thus, in the animals which possess the power of 
acting—namely, the force productive of movements 
and actions—the inner feeling, which on each oc- 
casion originates this force, being excited by some 
need, places in action the power or force in question ; 
excites the movement of displacement in the subtile 
fluid of the nerves—which the ancients called axzmal 
spirits; directs this fluid towards that of its organs 
which any want impels to action; finally makes this 
same fluid flow back into its habitual reservoirs when 
the needs no longer require the organ to act. 
“The inner feeling takes the place of the wd; 
for it is now important to consider that every 
animal which does not possess the special organ 
in which or by which it executes thoughts, judg- 
ments, etc., has in reality no will, does not make a 
choice, and consequently cannot control the move- 
ments which its inner feeling excites. J/zstznct directs 
these actions, and we shall see that this direction al- 
ways results from emotions of the inner feeling, in 
which intelligence has no part, and from the organ- 
ization even which the habits have modified, in such 
a manner that the needs of animals which are in this 
