278 THE METAPHYSICS OF SENSATION 



But while the " New Theory of Vision " cannot 

 be considered to possess much value in relation to 

 the immediate object its author had in view, it 

 had a vastly important influence in directing 

 attention to the real complexity of many of those 

 phenomena of sensation, which appear at first to 

 be simple. And even if Berkeley, as I imagine, 

 was quite wrong in supposing that we do not see 

 space, the contrary doctrine makes quite as strongly 

 for his general view, that space can be conceived 

 only as something thought by a mind. 



The last of Locke's " primary qualities " which 

 remain to be considered is mechanical solidity, or 

 impenetrability. But our conception of this is 

 derived from the sense of resistance to our own 

 effort, or active force, which we meet with in 

 association with sundry tactile or visual pheno- 

 mena ; and, undoubtedly, active force is incon- 

 ceivable except as a state of consciousness. This 

 may sound paradoxical ; but let any one try to 

 realize what he means by the mutual attraction of 

 two particles, and I think he will find, either, that 

 he conceives them simply as moving towards one 

 another at a certain rate, in which case he only 

 pictures motion to himself, and leaves force aside ; 

 or, that he conceives each particle to be animated 

 by something like his own volition, and to be 

 pulling as he would pull. And I suppose that 

 this difficulty of thinking of force except as some- 

 thing comparable to volition lies at the bottom of 



