OBSERVATION AND DESCRIPTION. 451 



Other, which is deceived ; the deception, whether durable or only momentary, 

 is in my judgment. From my senses I have only the sensations, and those 

 are genuine. Being accustomed to have those or similar sensations when, 

 and only when, a certain arrangement of outward objects is present to my 

 organs, I have the habit of instantly, when I experience the sensations, in- 

 ferring the existence of that state of outward things. This habit has be- 

 come so powerful, that the inference, performed with the speed and certainty 

 of an instinct, is confounded with intuitive perceptions. When it is cor- 

 rect, I am unconscious that it ever needed proof ; even when I know it to 

 be incorrect, I can not without considerable effort abstain from making it. 

 In order to be aware that it is not made by instinct but by an acquired hab- 

 it, I am obliged to i-eflect on the slow process through which I learned to 

 judge by the eye of many things which I now appear to j)erceive directly 

 by sight; and on the reverse operation performed by persons learning to 

 draw, who with difficulty and labor 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 ex- 

 patiate 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 sensations by which 

 we recognize 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 diagnos- 

 tics, to the entire phenomenon. And hence, among other consequences, fol- 

 lows the seeming paradox, that a general proposition collected from par- 

 ticulars is often more certainly true than any one of the particular propo- 

 sitions 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 can not 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 than 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 re- 

 quires no further 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 consciousness, namely, its outward 

 feelings or sensations, and its inward feelings — its thoughts, emotions, and 

 volitions. Whether any thing else remains, or all else is inference from 

 this ; whether the mind is capable of directly perceiving or apprehending 

 any thing except states of its own consciousness — is a problem of meta- 

 physics not to be discussed in this place. But after excluding all questions 

 on which metaphysicians differ, it remains true, that for most purposes the 

 discrimination we are called upon practically to exercise is that between 

 sensations or other feelings, of our own or of other people, and inferences , 

 drawn from them. And on the theory of Observation this 

 seems necessaiy to be said for the purposes of the present 



