SPACE 25 



experience will teach us whether this is so. But it is certainly 

 not an axiom. 



All that is certain is that every physical analysis must pro- 

 ceed from this indivisible, smallest space-receptacle, without 

 form or substance ; and it must end there, because at that 

 point our own organisation has set the limit to investigation. 

 So long as by the aid of optics we are enabled to magnify the 

 smallest particles of matter yet known, just so long will our 

 local signs go on creating fresh atoms. The limit to this is 

 purely practical. There is no theoretical limit to the practical 

 application of local signs. 



Summarising, we may make the following definitions : — 

 As the point of intersection of two series of direction-signs, a 

 mathematical point is a point in space that has no extension ; 

 a local sign is the smallest spatial magnitude ; an atom, as 

 the association of a local sign with a sense-quality, indicates 

 a material point in space. 



GLANCING AND SEEING 



By this time we have been able to establish an almost 

 complete parallel between the functions of touch and sight. 

 We even speak metaphorically of " sweeping " objects with 

 the eye. But this very expression gives the clue to where 

 the difference between touch and sight is to be sought. 

 " Sweeping " an object means a movement of the hand or 

 eye in which only a few local sign^ come into activity. When 

 the eye is moving we call the employment of limited local 

 signs " glancing," and when the eye is stationary, " staring." 



In contrast to this, we describe the collective employment 

 of all the local signs as " looking." We know of no parallel 

 process for the act of touch, where all the local signs in 

 the skin come into activity simultaneously. 



In order to make glancing possible, a special contrivance 



