1855.] On Mental Education. 467 



one finger by the tip of the opposed one, all sorts of confusion 

 in the motion will ensue ; and as the finger of one hand tries, 

 under the instruction of the will, to move in one course, the 

 touched finger will convey an intimation that it is moving in 

 another. If all the fingers move at once, all will be in con- 

 fusion, the ease and simplicity of the first case having entirely 

 disappeared. If, after some considerable trial, familiarity 

 with the new circumstances have removed part of the un- 

 certainty, then, crossing the hands at the opposite sides of the 

 wrists will renew it. These contrary results are dependent 

 not on any change in the nature of the sentient indication, or 

 of the surfaces or substances which the sense has to deal with ; 

 but upon the trifling circumstance of a little variation from the 

 direction in which the sentient organs of these parts are usually 

 exerted ; and they show to what an extraordinary extent our 

 interpretations of the sense impressions depend upon the 

 experience, i. e. the education which they have previously 

 received, and their great inability to aid us at once in circum- 

 stances which are entirely new. 



At other times they fail us because we cannot keep a true 

 remembrance of former impressions. Thus, on the evening of 

 the llth of March last, I and many others were persuaded 

 that at one period the moon had a real green colour, and 

 though I knew that the prevailing red tints of the general sky 

 were competent to produce an effect of such a kind, yet there 

 was so little of that in the neighbourhood of the planet, that I 

 was doubtful whether the green tint was not produced on the 

 moon by some aerial medium spread before it ; until by holding 

 up white cards in a proper position, and comparing them with 

 our satellite, I had determined experimentally that the effect 

 was only one of contrast. In the midst of the surrounding 

 tints, my memory could not recall the true sentient impression 

 which the white of the moon most surely had before made 

 upon the eye. 



At other times the failure is because one impression is over- 

 powered by another ; for as the morning star disappears when 

 the sun is risen, though still above the horizon and shining 

 brightly as ever, so do stronger phenomena obscure weaker, 

 even when both are of the same kind ; till an uninstructed 

 person is apt to pass the weaker unobserved, and even deny 

 their existence. 



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