THE COMPOSITION OF MIND 



where the horizontal piece is fitted upon it, 

 awaken tactual sensations which coexist with 

 the sensation of temperature, and the automatic 

 comparison of these sensations which consti- 

 tutes the perception of the faucet goes on un- 

 hindered. To concentrate consciousness upon 

 the feeling of temperature requires a voluntary- 

 act of attention, induced by the desire to know 

 how wirm the water is getting. As the water 

 becomes very much warmer, so as to be slightly 

 uncomfortable, the perception of the faucet does 

 not become gradually less vivid, but it tends 

 to disappear entirely, and consciousness tends 

 to occupy itself exclusively with the feeling of 

 temperature. Only through a distinct volun- 

 tary effort can the perception be made to come 

 into the foreground of consciousness. If now 

 there comes a sudden spurt of very hot water, 

 the tactual perception of the faucet is for the 

 moment entirely excluded, and the perceptive 

 act implied in the estimation of the degree of 

 temperature is also expelled from consciousness, 

 which is occupied entirely with the sensation of 

 pain, inducing a violent withdrawal of the hand. 

 Here sensation, reaching a maximum, has quite 

 driven out the group of tactual perceptions, 

 and even visual perceptions are to that extent 

 held in abeyance, that for the moment they 

 cease to occupy the attention. If now a piece 

 of soap is taken from its dish, the newly aroused 

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