xii.] THE METAPHYSICS OF SENSATION. 305 



sections of the " Theory of Vision," in which he endea- 

 vours to prove that a pure intelligence 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 proportions 

 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 contradictory to his own previously 

 cited admissions ; if he only means, on tho 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 contra- 

 diction 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 Berke- 

 ley'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 distinguish between a cube and a 

 sphere, could; on receiving his sight, tell the one from 

 the other by vision. Berkeley agrees with Locke that 

 he could not, and adds the following reflection : 



" Cube, sphere, table, are words he has known applied to things 

 perceivable by touch, but to things perfectly intangible he never 

 knew them applied. Those words in their wonted application always 



