186 OPERATIONS SUBSIDIARY TO INDUCTION. 



which I now appear to perceive directly by sight ; and on the 

 reverse operation performed by persons learning to draw, who 

 with difficulty and labour divest themselves of their acquired 

 perceptions, and learn afresh to see things as they appear to 

 the eye. 



It would be easy to prolong these illustrations, were 

 there any need to expatiate on a topic so copiously exemplified 

 in various popular works. From the examples already given, 

 it is seen sufficiently, that the individual facts from which we 

 collect our inductive generalizations are scarcely ever obtained 

 by observation alone. Observation extends only to the sen- 

 sations by which we recognise objects ; but the propositions 

 which we make use of, either in science or in common life, 

 relate mostly to the objects themselves. In every act of what 

 is called observation, there is at least one inference from the 

 sensations to the presence of the object; from the marks or 

 diagnostics, to the entire phenomenon. And hence, among 

 other consequences, follows the seeming paradox, that a 

 general proposition collected from particulars is often more 

 certainly true than any one of the particular propositions from 

 which, by an act of induction, it was inferred. For, each of 

 those particular (or rather singular) propositions involved an 

 inference, from the impression on the senses to the fact which 

 caused that impression : and this inference may have been 

 erroneous in any one of the instances, but cannot well have 

 been erroneous in all of them, provided their number was 

 sufficient to eliminate chance. The conclusion, therefore, that 

 is, the general proposition, may deserve more complete reliance 

 tnan it would be safe to repose in any one of the inductive 

 premises. 



The logic of observation, then, consists solely in a correct 

 discrimination between that, in a result of observation, which 

 has really been perceived, and that which is an inference from 

 the perception. Whatever portion is inference, is amenable to 

 the rules of induction already treated of, and requires no fur- 

 ther notice here : the question for us in this place is, when 

 all which is inference is taken away, what remains. There 

 remains, in the first place, the mind's own feelings or states of 



