VISION 395 



It lies about it in a downright ingenuous fashion if it is con- 

 fident of credence, in a more subtle way if a simple falsehood is 

 likely to be challenged. In place of the black disc make nine 

 conspicuous crosses : 



XXX 

 X X X 

 XXX 



Hold the paper in such a position that X falls upon the blind 

 spot. It ought to disappear, but the mind assures you that 

 there is a cross at that spot. The mind completes the field. 

 In place of the crosses use noughts and crosses, thus : 



0X0 

 X X X 

 0X0 



Now let X fall on the blind spot, and allow the eye to go just 

 a little out of focus. The four marginal crosses draw inwards : 







X X 



X 



O 



The mind contracts the field. Still denying the gap, but not 

 having sufficient data from which to invent an object, the 

 fraudulent nature of which would not be found out the instant 

 that the gaze is shifted, the mind lies regarding the position on 

 the paper occupied by surrounding objects. 



Is it quite fair to the mind to say that it lies about the 

 blind spot ? The mind judges sensations in the light of 

 experience. An association of previous sensations teaches me 

 that the wall of the room is not pierced by a round hole a foot 

 in diameter opening into outer darkness. Many sensations 



