THE PERCEPTION OF SPACE. 185 



Different impressions on the same sense-organ do interfere 

 with each other's perception, and cannot well be attended 

 to at once. Hence ive do not locate them in each other s spaces, 

 but arrange them in a serial order of exteriority, each alongside 

 of the rest, in a space larger than that which any one sensation 

 brings. This larger space, however, is an object of concep- 

 tion rather than of direct intuition, and bears all the marks 

 of being constructed piecemeal by the mind. The blind 

 man forms it out of tactile, locomotor, and auditory experi- 

 ences, the seeing man out of visual ones almost exclusively. 

 As the visual construction is the easiest to understand, 

 let us consider that first. 



Every single visual sensation or ' held of view ' is 

 limited. To get a new field of view for our object the old 

 one must disappear. But the disappearance may be only 

 partial. Let the first field of view be A B C. If we carry 

 our attention to the limit C, it ceases to be the limit, and 

 becomes the centre of the field, and beyond it appear fresh 

 parts where there were none before : * ABC changes, in 

 short, to C D E. But although the parts A B are lost to 

 sight, yet their image abides in the memory ; and if we think 

 of our first object ABC as having existed or as still existing 

 at all, we must think of it as it was originally presented, 

 namely, as spread out from C in one direction just as C D E 

 is spread out in another. A B and D E can never coalesce 

 in one place (as they could were they objects of difierent 

 senses) because they can never be perceived at once : we 

 must lose one to see the other. So (the letters standing 

 now for ' things ') we get to conceive of the successive fields 

 of things after the analogy of the several things which we 

 perceive in a single field. They must be out- and along- 

 side of each other, and we conceive that their juxtaposed 

 spaces must make a larger space. A B C + C D E must, 

 in. short, be imagined to exist in the form of A B C D E or 

 not imagined at all. 



We can usually recover anything lost from sight by 

 moving our attention and our eyes back in its direction ; and 



* Cf. Shand, in Mind, xiii. 340. 



