GENERAL PRINCIPLES 49 



in that respect, having no other faculty but those of life in general, 

 and being unable to move except by a power outside thera ; Avhile 

 others have faculties, progressively more numerous and important, 

 up to the most perfect animals, which exhibit a capacity calculated 

 to excite our wonder. 



These remarkable facts no longer surprise us, when we recognise 

 that every faculty is based upon some special organ or system of organs, 

 and when we observe that organisation gradually becomes more 

 complex as we pass from the most imperfect animal, which has no 

 special organ whatever and consequently no faculty but those of 

 life in general, to the most perfect and richly endowed animal. Thus 

 all the organs, even the most important, arise one after the other in 

 the animal scale, and afterwards become successively more perfect 

 through the modifications impressed on them, by which these organs 

 come to harmonise with the state of organisation of which they are 

 part. Hence, by their combination in the most perfect animals, 

 they constitute the highest degree of organisation, giving rise to the 

 most numerous and important faculties. 



The examination of the internal organisation of animals ; of the 

 various systems presented by that organisation in the animal scale ; 

 and, finally, of the special organs, is then the subject of study most 

 deserving of our attention. 



If animals, considered as productions of nature, are rendered 

 extremely remarkable by their faculty of locomotion, a great many of 

 them are still more so by their faculty of feeling. 



I have said that this faculty of locomotion is very limited in the most 

 imperfect animals, among which it is not voluntary and is only carried 

 out by external stimuli. It then becomes gradually more perfect 

 and ultimately takes its source within the animal itself, and becomes 

 at length subject to its will. In just the same way, the faculty of feeling 

 is still very obscure and limited in the animals among which it begins 

 to exist ; but it then develops gradually, and when it has reached its 

 highest development it ultimately gives rise in the animal to the 

 faculties which constitute intelligence. 



Indeed the most perfect among animals have simple and even com- 

 plex ideas ; they have passions and memory and they dream, that is 

 to say, they experience involuntary recurrences of their ideas and 

 even of their thoughts ; and they are up to a certain point capable 

 of learning. How wonderful is this result of the power of nature ! 



Nature thus succeeds in endowing a living body with the faculty 

 of locomotion, without the impulse of an external force ; of perceiving 

 objects external to it ; of forming ideas by comparison of impres- 

 sions received from one object with those received from others ; of 



