THE METAPHYSICS OF SENSATION 267 



gence able to see, but devoid of the sense of touch, 

 could have no idea of a plane figure. Thus he 

 says in section 156 : 



"All that is properly perceived by the visual faculty amounts 

 to no more than colours with their variations and different pro- 

 portions of light and shade ; but the perpetual mutability and 

 fleetingness of those immediate objects of sight render them 

 incapable of being managed after the manner of geometrical 

 figures, nor is it in any degree useful that they should. It is 

 true there be divers of them perceived at once, and more of some 

 and less of others ; but accurately to compute their magnitude, 

 and assign precise determinate proportions between things so 

 variable and inconstant, if we suppose it possible to be done, 

 must yet be a very trifling and insignificant labour." 



If, by this, Berkeley means that by vision alone, 

 a straight line cannot be distinguished from a 

 curved one, a circle from a square, a long line 

 from a short one, a large angle from a small one, 

 his position is surely absurd in itself and contra- 

 dictory to his own previously cited admissions ; if 

 he only means, on the other hand, that his pure 

 spirit could not get very far on in his geometry, it 

 may be true or not ; but it is in contradiction 

 with his previous assertion, that such a pure spirit 

 could never attain to know as much as the first 

 elements of plane geometry. 



Another source of confusion, which arises out of 

 Berkeley's insufficient exactness in the use of 

 language, is to be found in what he says about 

 solidity, in discussing Molyneux's problem, whether 

 a man born blind and having learned to dis- 



