206 MATHEMATICAL MODES OF 



hitherto proceeded in this way ; knowing the habits of the 

 animals, and the form of the skeleton, and arrangement of the 

 muscles which co-operate with it in performing the movements 

 of the animals, they sought to determine what the particular 

 economy of the animal, under certain conditions, required. It 

 should be remembered that there was always a corresponding 

 harmony between the shape and connections of the organs of 

 the body and the motions peculiar to the animal. This in- 

 volves the principle of final causes, which entered so largely 

 into anatomical and physiological investigations. Upon this 

 principle we determined what were the functions, because there 

 was no other the parts were so well adapted to perform. 



The wonderful progress of biology the science compre- 

 hending the study of anatomy and physiology or of compara- 

 tive anatomy, was attributable to this ; it owed its greatness 

 to this study of final causes that of the remarkable adapta- 

 tion of structures to particular functions. 



The application of the doctrine of final causes was not, 

 however, the most fertile mode of procedure in physical inves- 

 tigations. It was only with respect to organised bodies that 

 it had enabled men of science to advance human knowledge. 

 It was very different in regard to chemistry, mechanics, etc., 

 where no progress had been made till men of science had 

 thrown aside the consideration of final causes. But although 

 physical science did not advance till the introduction of the 

 inductive philosophy, and till final causes had been laid aside, 

 still the principle of final causes pervaded all nature. Take 

 in illustration the sun. But for the peculiar arrangement of the 

 sun in regard to the relations which he holds towards the earth 

 and other planetary bodies, his shape, and manner of moving 

 on his axis, we could have neither heat nor darkness, which 

 the economy of animals and vegetables rendered absolutely 

 necessary. Thus we might reason of the sun and earth, etc., 

 from final causes, and might explain why the sun was so con- 



