TRAINS OF REASONING. 281 



one of those to which, if then known, the induction 

 would have been deemed to extend. These marks 

 we either recognise at once, or by the aid of other 

 marks, which by another previous induction we col- 

 lected to be marks of them. Even these marks of 

 marks may only be recognised through a third set 

 of marks ; and we may have a train of reasoning, 

 of any length, to bring a new case within the 

 scope of an induction grounded on particulars its 

 similarity to which is only ascertained in this indirect 

 manner. 



Thus, in the argument concerning the Prussian 

 government, the ultimate inductive inference was, 

 that it was not liable to revolution : this inference was 

 drawn according to a formula in which desire of the 

 public good was set down as a mark of not being 

 liable to revolution ; a mark of this mark was, acting 

 in a particular manner ; and a mark of acting in that 

 manner, was, being asserted to do so by many disin- 

 terested witnesses : this mark, the Prussian govern- 

 ment was recognised by the senses as possessing. 

 Hence that government fell within the last induction, 

 and by it was brought within all the others. The 

 perceived resemblance of the case to one set of 

 observed particular cases, brought it into known 

 resemblance with another set, and that with a third. 



In the more complex branches of knowledge, the 

 deductions seldom consist, as in the examples hitherto 

 exhibited, of a single chain, a a mark of b, b of c, c 

 of d, therefore a a mark of d. They consist (to carry 

 on the same metaphor) of several chains united at the 

 extremity, as thus : a a mark of d, b of e, c of /, 

 d ef of ra, therefore a b c a mark of n. Suppose, for 

 example, the following combination of circumstances: 

 1st, rays of light impinging on a reflecting surface; 



