THE SIX GATEWA YS OF KNOWLEDGE. 257 



them. Let me dip my hand into this bowl of 

 hot water. The moment I touch the water, I 

 perceive a very distinct sensation, a sensation of 

 heat. Is that a sensation of roughness, or of 

 smoothness ? No. Again, I dip my hand into 

 this basin of iced water. I perceive a very distinct 

 sensation. Is this a sensation of roughness, or of 

 smoothness ? No. Is this comparable with that 

 former sensation of heat ? I say yes. Although 

 it is opposite, it is comparable with the sensation 

 of heat. I am not going to say that we have two 

 sensations in this department ; a sensation of heat, 

 and a sensation of cold. I shall endeavour to 

 explain that the perceptions of heat and cold 

 are perceptions of different degrees of one and 

 the same quality, but that that quality is markedly 

 different from the sense of roughness. Well now, 

 what is this sense of roughness ? It will take me 

 some time to explain it fully. I shall therefore 

 say in advance, that it is a sense of force ; and I 

 shall tell you in advance, before I justify com- 

 pletely what I have to say, that the six senses, 

 regarding which I wish to give some explanation, 



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