272 INDUCTION. 



§ 3. A second case is when, between what seemed the cause and 

 what was supposied to be its effect, further observation detects an in- 

 termediate hnk ; a fact caused by the antecedent, and in its turn caus- 

 ing the consequent ; so that the cause at first assigned is but the remote 

 cause, operating through the intermediate phenomenon. A seemed 

 the cause of C, but it subsequently appeared that A was only the cause 

 of B, and that it is B which was the cause of C. For example: man- 

 kind were aware that the act of touching an outward object caused a 

 sensation. It was, however, at last discovered, that after we have 

 touched the object, and before we experience the sensation, some 

 change takes place in a kind of thread called 9. nerve, which extends 

 from our outward organs to the brain. Touching the object, therefore, 

 is only the remote cause of our sensation; that is, not the cause, prop- 

 erly speaking, but the cause of the cause : the real cause of the sensa- 

 tion is the change in the state of the nerve. Future experience may not 

 only give us more knowledge than we now have of the particular 

 nature of this change, but may also interpolate another link : between 

 the contact (for example) of the object with our outward organs, and 

 the production of the change of state in the nerve, there may take 

 place some electric phenomenon. Hitherto, however, no such inter- 

 mediate agency has been discovered ; and the touch of the object must 

 be considered, provisionally at least, as the proximate cause of the 

 affection of the nerve. The sequence, therefore, of a sensation of 

 touch upon contact with an object, is ascertained not to be an ultimate 

 law ; is resolved, as the phrase is, into two other laws — the law, that 

 contact with an object produces an affection of the neiTe ; and the law, 

 that an affection of the nerve produces sensation. 



To take another example : the more powerful acids corrode or black- , 

 en organic compounds. This is a case of causation, but of remote causa- 

 tion ; and is said to be explained when it is shown that there is an inter- 

 mediate link, namely, the separation of some of the chemical elements of 

 the organic structure from the rest, and their entering into combination 

 with the acid. The acid causes this separation of the elements, and the 

 separation of the elements causes the disorganization, and often the 

 charring of the structure. So, again, chlorine extracts coloring mat- 

 ters (whence its efficacy in bleaching), and purifies the air from infec- 

 tion, .This law is resolved into the two following laws. Chlorine haa 

 a powerful affinity for bases of all kinds, particularly metallic bases 

 and hydrogen. Such bases are essential elements of coloring matters 

 and contagious compounds ; whicli substances-, therefore, are decom- 

 posed and destroyed by chlorine. 



§ 4. It is of importance to remark, that when a sequence of phe- 

 nomena is thus resolved into other laws, they are always laws more 

 general than itself The law that A is followed by C, is less general 

 Sian either of the laws which connect B with C and A with B. This 

 vdll appear from very simple considerations. 



All laws of causation ai-e liable to be counteracted, or frustrated, by 

 the non-fulfilment of some negative condition : the tendency, therefore, 

 of B to produce C may be defeated. Now the law that A produces 

 B, is equally fulfilled whether B is followed by C or not ; but the law 

 that A produces C by means of B, is of course only fulfilled Avhen B 

 is really followed by C, and is therefore less general than the law that 



