ACTIONS OF ANIMALS 347 



with the intimate feeling of their existence ; and henceforward the 

 force productive of movements was transferred into the interior of 

 the animal itself. 



I have already shown that this internal force, which produces 

 movements and actions, finds its origin in the intimate feeling of 

 existence possessed by animals which have a nervous system, and that 

 this feeling when aroused by the needs sets in motion the subtle fluid 

 contained in the nerves, and drives it to the muscles which have to 

 act ; thus are produced the actions which the needs demand. 



Now every need that is felt, produces an emotion in the individual's 

 inner feeling ; and from this emotion springs the force which gives 

 rise to the movements required. I furnished evidence of this in 

 setting forth the communication and harmony existing throughout 

 the nervous system, and the way in which the inner feeling on being 

 stirred may excite muscular activity. 



Hence, in animals which contain within them the force productive 

 of movements and actions, the inner feeling which gives rise to that 

 force puts it in action, whenever some need is felt, and thus excites 

 movements in the subtle fluid of the nerves (called by the ancients 

 animal spirits) ; the force directs that fluid towards such of the organs 

 as have to act, and finally causes a reflux of the fluid into its usual 

 reservoirs, when the needs no longer require the organ to act. 



The inner feeling then takes the place of will ; for it now becomes 

 important to remember that every animal which does not possess 

 the special organ in which or by means of which thoughts, judgments, 

 etc., are produced, has really no will, does not choose, and therefore 

 cannot control the movements, prompted by its intimate feeling. 

 Instinct directs these movements, and we shall see that this direction 

 always results from emotions of the inner feeling, in which the intellect 

 has no share, and from the organisation as modified by habit ; so 

 that the needs of such animals being necessarily limited and always 

 the same in the same species, the intimate feehng always produces 

 the same actions. 



The case is different in animals which nature has endowed with an 

 additional special organ (two wrinkled hemispheres surmounting the 

 brain), for the performance of acts of intelligence, and which con- 

 sequently carry out comparisons, judgments, thoughts, etc. These 

 animals control their power of acting in proportion to the perfection 

 of their organ of intelligence ; and although they are still strongly 

 subordinated to the habits which have modified their organisation, 

 they yet enjoy a will that is more or less free; they can choose, and 

 introduce variation into their actions or at least into some of them. 



We shall now say a word about the consumption of the nervous 



