xiii.] THE METAPHYSICS OF SENSATION. 343 



same way as with the moveable hand ; and the notion 

 of change of place, plus the sense of effort, gives rise to a 

 conception of visual space, which runs exactly parallel 

 with that of tangible space. When two moveable eyes 

 are present, the notion of space of three dimensions is 

 obtained in the same way as it is by the two hands, but 

 with much greater precision. 



And if, to take a case similar to one already assumed, 

 we suppose a man deprived of every sense except vision, 

 and of all motion except that of his eyes, it surely cannot 

 be doubted that he would have a perfect conception of 

 space ; and indeed a much more perfect conception than 

 he who possessed touch alone without vision. But of 

 course our touchless man would be devoid of any notion 

 of resistance ; and hence space, for him, would be alto- 

 gether geometrical and devoid of body. 



And here another curious consideration arises, what 

 likeness, if any, would there be between the visual space 

 of the one man, and the tangible space of the other ? 



Berkeley, as we have seen (in the eighth proposition), 

 declares that there is no likeness between the ideas given 

 by sight and those given by touch ; and one cannot but 

 agree with him, so long as the term ideas is restricted to 

 mere sensations. Obviously, there is no more likeness 

 between the feel of a surface and the colour of it, than 

 there is between its colour and its smell. All simple 

 sensations, derived from different senses, are incommen- 

 surable with one another, and only gradations of their 

 own intensity are comparable. And thus so far as the 

 primary facts of sensation go, visual figure and tactile 

 figure, visual magnitude and tactile magnitude, visual 

 motion and tactile motion, are truly unlike, and have no 

 common term. But when Berkeley goes further than 

 this, and declares that there are no " ideas " common 

 to the " ideas " of touch and those of sight, it appears to 



