414 ACTUAL WORKING IN ORIGINAL RESEARCH. 



nical force, heat, &c., whilst others are more limited ; 

 as, for example, the vital power. The most general of 

 causes are capable of producing an immense number of 

 effects; thus mechanical power can produce motion in 

 every existing ponderable substance, but special causes 

 have more limited action ; vital power operates only in 

 what are termed living things. 



There are also primary or immediate causes, or those 

 directly connected with the effect ; secondary, proximate, 

 and intermediate ones, or those constituting the inter- 

 vening links in a chain of causation ; and remote causes, 

 or those only distantly connected with the effect through 

 many others. As a chain is only as strong as its weakest 

 link, so in a series of dependent phenomena the final 

 effect is only certain provided all the intermediate ones 

 are sure. The final effect, however, is not rendered less 

 certain by mere greatness of number of intervening phe- 

 nomena, provided each of the connections is secure, other- 

 wise the physical and chemical changes occurring in the 

 present age would be less determinate than those in past 

 times. Persons who are unwilling to admit the certainty 

 of action of remote causes might with advantage re- 

 member that we are all of us as certainly the children of 

 Adam as of our immediate progenitors. The great prin- 

 ciples of continuity, indestructibility, and equivalence of 

 matter and force determine the certainty and non-diminu- 

 tion of effect by lapse of time. 



As matter is the seat of causation, complexity of ma- 

 terial structure indicates complexity of action of causes 

 within or upon it. Simple structures are also usually 

 more stable than complex ones, and will often bear the 

 greatest change of temperature without being decom- 

 posed. There is more mutual dependence in organic 

 bodies than in inorganic ones. Cerebral matter is the 



