INTRODUCTORY REMARKS. 9 



antecedent effect ; and our reasoning as applied to the suc- 

 cessive production of all natural changes would be the same. 



Habit and the identification of thoughts with phenomena 

 so compel the use of recognised terms, that we cannot avoid 

 using the word ' cause ' even in the sense in which objection is 

 taken ; and if we struck it out of our vocabulary, our lan- 

 guage, in speaking of successive changes, would be unintelli- 

 gible to the present generation. The common error, if I am 

 right in supposing it to be such, consists in the abstraction of 

 cause, and in supposing in each case a general secondary 

 cause a something which is not the first cause, but which, if 

 we examine it carefully, must have all the attributes of a 

 first cause, and an existence independent of, and dominant 

 over, matter. 



The relations of electricity and magnetism afford us a very 

 instructive example of the belief in secondary causation. Sub- 

 sequent to the discovery by Oersted of electro-magnetism, and 

 prior to that by Faraday of magneto-electricity, electricity 

 and magnetism were believed by the highest authorities to 

 stand in the relation of cause and effect i.e. electricity was 

 regarded as the cause, and magnetism as the effect; and where 

 magnets existed without any apparent electrical currents to 

 cause their magnetism, hypothetical currents were supposed, 

 for the purpose of carrying out the causative view ; but mag- 

 netism may now be said with equal truth to be the cause of 

 electricity, and electrical currents may be referred to hypothe- 

 tical magnetic lines : if therefore electricity cause magnetism, 

 and magnetism cause electricity, why then electricity causes 

 electricity, which becomes, so as to speak, a rcditctio ad 

 absurdum of the doctrine. 



To take another instance, which may render these posi- 

 tions more intelligible. By heating bars of bismuth and anti- 

 mony in contact, a current of electricity is produced ; and if 

 their extremities be united by a fine wire, the wire is heated. 

 Now, here the electricity in the metals is said to be caused by 

 heat, and the heat in the wire to be caused by electricity, and 

 in a concrete sense this is true ; but can we thence say ab- 

 stractedly that heat is the cause of electricity, or that elec- 

 tricity is the cause of heat ? Certainly not ; for if either be 



