ABSTRACTION. 223 



not only of much greater importance in themselves, 

 but are marks of agreements and differences in many 

 other most important particulars of the structure and 

 mode of life of the animals. If, therefore, the study 

 of their structure and habits be our object, the con- 

 ceptions generated by these last comparisons are far 

 more "appropriate'' than those generated by the 

 former. Nothing, other than this, can be meant by 

 the appropriateness of a conception. 



When Mr. Whewell says that the ancients, or the 

 schoolmen, or any modern philosophers, missed dis- 

 covering the real law of a phenomenon because they 

 applied to it an inappropriate instead of an appro- 

 priate conception ; he can only mean that in com- 

 paring various instances of the phenomenon, to ascer- 

 tain in what those instances agreed, they missed the 

 important points of agreement ; and fastened upon such 

 as were either imaginary, and no agreements at all, or 

 if real agreements, were comparatively trifling, and 

 had no connexion with the phenomenon, the law of 

 which was sought. 



Aristotle, philosophizing on the subject of motion, 

 remarked that certain motions apparently take place 

 spontaneously; bodies fall to the ground, flame 

 ascends, bubbles of air rise in water, &c. : and these he 

 called natural motions ; while others not only never 

 take place without external incitement, but even when 

 such incitement is applied, tend spontaneously to 

 cease; which, to distinguish them from the former, he 

 called violent motions. Now, in comparing the so- 

 called natural motions with one another, it appeared 

 to Aristotle that they agreed in one circumstance, 

 namely, that the body which moved (or seemed to 

 move) spontaneously, was moving towards its own 

 place; meaning thereby the place from whence it 



