180 ZOOLOGICAL PHILOSOPHY 



longer than the duration of human life are easily recognised by an 

 observer, but he could not perceive any of those whose occurrence 

 consumes a long period of time. 



To explain what I mean let me make the following supposition. 



If the duration of human hfe only extended to one second, and if 

 one of our ordinary clocks were wound up and set going, any individual 

 of our species who looked at the hour hand of this clock would detect 

 in it no movement in the course of his life, although the hand is not 

 really stationary. The observations of thirty generations would 

 furnish no clear evidence of a displacement of the hand, for it would 

 only have moved through the distance traversed in half a minute and 

 this would be too small to be clearly perceived ; and if still older 

 observations showed that the hand had really changed its position, 

 those who heard this proposition enunciated would not believe it, 

 but would imagime some mistake, since they had always seen the hand 

 at the same point of the dial. 



I leave my readers to apply this analogy to the subject in hand. 



Nature — that immense assemblage of various existences and bodies, 

 in all whose parts continually proceeds an eternal cycle of movements 

 and changes controlled by laws — an assemblage that is only immutable 

 so long as it pleases her Sublime Author to continue her existence — 

 should be regarded as a whole made up of parts, with a purpose that 

 is known to its Author alone, but at any rate not for the sole benefit 

 of any single part. 



Since each part must necessarily change and cease to exist to make 

 way for the formation of another, each part has an interest which is 

 contrary to that of the whole ; and if it reasons, it finds that the whole 

 is badly made. In reahty, however, this whole is perfect, and com- 

 pletely fulfils the purpose for which it is destined. 



