OF FUNCTION; OR, HOW WE ACT. 17 



peculiar characteristic belonging to the nature of the 

 engine ? and when, after a long time, the expansion 

 of the steam coincident with this motion was detected, 

 might it not have been at first regarded as conse- 

 quence, and not as cause ? Can we imagine persons 

 thus studying the steam-engine backwards, and in- 

 verting the relation of the facts ? If we can, then 

 we liaVe a representation of the course of discovery 

 in respect to the vital functions. The animal body 

 came before men's senses as gifted with a power of 

 acting; this was, to their thoughts, its nature 

 a property of life. They grew familiar with this 

 "property," and ceased to demand a cause or ex- 

 planation of it, long before it was discovered that 

 with every such exhibition of power there was con- 

 nected a change in its composition. Only after long 

 study, and through knowledge of many laws, was 

 this discovery made. How then should they have 

 done otherwise than put the effect before the cause, 

 and say, " The animal body has an active power, 

 and as a consequence of every exertion of that power, 

 a part of its substance becomes decomposed ? " 



This is another reason why the parallel between 



2 



