XH. J THE METAPHYSICS OF SENSATION. 299 



that co-existence, number, and distance can have any 

 existence apart from the mind of which they are ideas. 



Thus it seems clear that the existence of some, at any 

 rate, of Locke s primary qualities of matter, such as 

 number and extension, apart from mind, is as utterly 

 unthinkable as the existence of colour and sound under 

 like circumstances. 



Will the others namely, figure, motion and rest, and 

 solidity withstand a similar criticism ? I think not. 

 For all these, like the foregoing, are perceptions by the 

 mind of the relations of two or more* sensations to one 

 another. If distance and place are inconceivable, in the 

 absence of the mind of which they are ideas, the inde 

 pendent existence of figure, which is the limitation of 

 distance, and of motion, which is change of place, must 

 be equally inconceivable. Solidity requires more par 

 ticular consideration, as it is a term applied to two very 

 different things, the one of which is solidity of form, 

 or geometrical solidity ; while the other is solidity of 

 substance, or mechanical solidity. 



If those motor nerves of a man by which volitions are 

 converted into motion were all paralysed, and if sensa 

 tion remained only in the palm of his hand (which is a 

 conceivable case), he would still be able to attain to 

 clear notions of extension, figure, number, and motion, by 

 attending to the states of consciousness which might be 

 aroused by the contact of bodies with the sensory surface 

 of the palm. But it does not appear that such a person 

 could arrive at any conception of geometrical solidity. 

 For that which does not come in contact with the 

 sensory surface is non-existent for the sense of touch ; 

 and a solid body, impressed upon the palm of the hand, 

 gives rise only to the notion of the extension of that 

 particular part of the solid which is in contact with 

 the skin. 



