XIIL] THE METAPHYSICS OF SENSATION. 335 



of that conception of space of three dimensions which 

 we obtain by the sense of touch ; and if that freedom to 

 move is really another name for the feeling of unopposed 

 effort, accompanied by that of change of place, it is surely 

 impossible to conceive of such space as having existence 

 apart from that which is conscious of effort. 



But it may be said that we derive our conception of 

 space of three dimensions not only from touch, but from 

 vision ; that if we do not feel things actually outside us, 

 at any rate we see them. And it was exactly this diffi- 

 culty which presented itself to Berkeley at the outset of 

 his speculations. He met it, with characteristic bold- 

 ness, by denying that we do see things outside us ; and, 

 with no less characteristic ingenuity, by devising that 

 "New Theory of Vision" which has met with wider 

 acceptance than any of his views, though it has been the 

 subject of continual controversies. 1 



In the "Principles of Human Knowledge," Berkeley 

 himself tells us how he was led to those views which 

 he published in the "Essay towards the New Theory 

 of Vision." 



" It will be objected that we see things actually without, or at 

 a distance from us, and which consequently do not exist in the mind ; 

 it being absurd that those things which are seen at the distance of 

 several miles, should be as near to us as our own thoughts. In answer 

 to this, I desire it may be considered that in a dream we do oft perceive 

 things as existing at a great distance off, and yet, for all that, those 

 things are acknowledged to have their existence only in the mind. 



" But for the fuller clearing of this point, it may be worth while to 

 consider how it is that we perceive distance and things placed at a 

 distance by sight. For that we should in truth see external space 

 and bodies actually existing in it, some nearer, others further off, 



1 I have not specifically alluded to the writings of Bailey, Mill, Abbott, and 

 others, on this vexed question, not because I have failed to study them carefully, 

 but because this is not a convenient occasion for controversial discussion. 

 Those who are acquainted with the subject, however, will observe that the view 

 I have taken agrees substantially with that of Mr. Bailey. 



