PRELIMINARY DISCOURSE 11 



an enquiry into the causes of life, of physical and moral sensitiveness, 

 and, in short, of the lofty functions which he possesses. It was first 

 necessary to try to acquire knowledge of the organisation of the other 

 animals. It was necessary to consider the differences which exist 

 among them in this respect, as well as the relationships which are 

 found between their special functions and the organisation with which 

 they are endowed. 



These different objects should have been compared with one another 

 and with what is known of man. An examination should have been 

 made of the progression which is disclosed in the complexity of organisa- 

 tion from the simplest animal up to man, where it is the most complex 

 and perfect. The progression should also have been noted in the 

 successive acquisition of the different special organs, and consequently 

 of as many new functions as of new organs obtained. It might then 

 have been perceived how needs, at first absent and afterwards gradually 

 increasing in number, have brought about an incUnation towards 

 the actions appropriate to their satisfaction ; how actions becoming 

 habitual and energetic have occasioned the development of the organs 

 which execute them ; how the force which stimulates organic move- 

 ments can in the most imperfect animals exist outside of them and 

 yet animate them ; how that force has been subsequently transported 

 and fixed in the animal itself ; and, finally, how it has become the source 

 of sensibility, and last of all of acts of intelhgence. 



I may add that if this method had been followed, feeling would 

 certainly not have been looked upon as the general and immediate 

 cause of organic movements. It would never have been said that 

 life is a consequence of movements executed by virtue of sensations 

 received by various organs or otherwise ; nor that all vital move- 

 ments are brought about by impressions received by sensitive parts 

 (Rapport du physique et du moral de Vhomme, pp. 38 to 39, and 85). 



This cause would appear to be justified up to a certain point in the 

 most perfect animals, but if it held good with regard to all bodies 

 which enjoy life, they would all possess the faculty of feehng. Now 

 it could hardly be shown that this is the case in plants ; it could hardly 

 even be proved that it is the case in all known animals. 



The supposition of such a general cause does not seem to me justified 

 by the real methods of nature. When constituting Ufe, she had no 

 power to endow with that faculty the imperfect animals of the earUer 

 classes of the animal kingdom. 



With regard to living bodies, it is no longer possible to doubt that 

 nature has done everything httle by little and successively. 



Hence, among the various subjects which I intend to discuss in 

 the present work, I shall endeavour to make clear by the citation 



