6 ZOOLOGICAL PHILOSOPHY 



none of those that are known to me seem to conflict, and finally which 

 appears to me obviously borne out by plant life. It was therefore 

 for me a flood of light which disclosed to me the principal cause which 

 maintains movements and the life of organised bodies, and to which 

 animals owe all that animates them. 



I combined this consideration with the two preceding ones, namely, 

 that which concerns the result of the movement of fluids in the interior 

 of animals and that which deals with the effects of a change that is 

 maintained in the environment and habits of these beings. I could 

 thus seize the thread which connects the numerous causes of the 

 phenomena presented in animal organisation, and I soon perceived 

 the importance of this power in nature which preserves in new in- 

 dividuals all the changes in organisation acquired by their ancestors 

 as a result of their life and environment. 



Now I remarked that the movements of animals are never directly 

 communicated, but that they are always excited ; hence I recognised 

 that nature, although obliged at first to borrow from the environ- 

 ment the excitatory power for vital movements and the actions of 

 imperfect animals, was able by a further elaboration of the animal 

 organisation to convey that power right into the interior of these 

 beings, and that finally she reached the point of placing that same 

 power at the disposal of the individual. 



Such are the principal conclusions which I have endeavoured to 

 establish and develop in this work. 



This Zoological Philosophy thus sets forth the results of my studies 

 on animals, their characters both general and special, their organisa- 

 tion, the causes of their development and diversity, and the faculties 

 which they thence derive. In its composition I have made use of 

 the bulk of the material which I was collecting for a projected work 

 on living bodies under the title of Biology. This work will now remain, 

 so far as I am concerned, unwritten. 



The facts which I name are very numerous and definite, and the 

 inferences which I have drawn from them appeared to me sound 

 and necessary ; I am convinced therefore that it will be found difficult 

 to replace them by any others. 



The number of new theories expounded in the present work are 

 likely to give the reader an unfavourable impression, if only from 

 the fact that the commonly received beliefs do not readily give 

 way to any new ones which tend to contradict them. Now, since 

 the predominance of old ideas over new favour this prejudice, 

 especially when there is some contributory personal interest, it follows 

 that, whatever difficulties there may be in the discovery of new truths 

 in nature, there are still greater difficulties in getting them recognised. 



