OF NATURAL PHILOSOPHY. 83 



sometimes contradicted by it in a very extraordinary 

 and surprising manner, as when the voice is made to 

 seem to issue from an inanimate and motionless object 

 If we plunge our hands, one into ice-cold water, and 

 the other into water as hot as can be borne, and, 

 after letting them stay awhile, suddenly transfer 

 them both to a vessel full of water at a blood heat, 

 the one will feel a sensation of heat, the other of 

 cold. And if we cross the two first fingers of one 

 hand, and place a pea in the fork between them, 

 moving and rolling it about on a table, we shall 

 (especially if we close our eyes) be fully persuaded 

 we have two peas. If the nose be held while we 

 are eating cinnamon, we shall perceive no difference 

 between its flavour and that of a deal shaving. 



(73.) These, and innumerable instances we might 

 cite, will convince us, that though we are never de- 

 ceived in the sensible impression made by external 

 objects on us, yet in forming our judgments of them 

 we are greatly at the mercy of circumstances, 

 which either modify the impressions actually re- 

 ceived, or combine them with adjuncts which have 

 become habitually associated with different judg- 

 ments; and, therefore, that, in estimating the degree 

 of confidence we are to place in our conclusions, 

 we must, of necessity, take into account these modi- 

 fying or accompanying circumstances, whatever they 

 maybe. We do not, of course, here speak of deranged 

 organization ; such as, for instance, a distortion of the 

 eye, producing double vision, and still less of mental 

 delusion, which absolutely perverts the meaning of 

 sensible impressions. 



(74.) As the mind exists not in the place of sensi- 

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