SPACE 43 



— such speculations are left to the psychologist : we restrict 

 ourselves to the forms of space-intuition to which we, as 

 observers, are confined. 



MATTER AND FORCE IN SPACE 



Normally the three phases of spatial vision shade into one 

 another by imperceptible degrees. As regards the first two 

 phases, this is at once understandable, for while the eyes are 

 performing their convergent movements, the accommodation- 

 apparatus is also in action, so that things seen as solid bodies 

 may be brought into the right distance. 



But both kinds of activity have their limits, and if the 

 axes of the eyes are parallel and the accommodation-muscles 

 are relaxed, object-signs and distance-signs must come in, 

 in order to make spatial vision for long distance possible. 

 These signs owe their existence to no special arrangement of 

 the optical apparatus, but have to be acquired by us through 

 oft-repeated experience ; sometimes they must even be learnt 

 anew. I remember very well how, the first time I went out 

 after a severe attack of typhoid fever, the street, at about 

 fifteen or twenty paces in front of me, swayed to and fro 

 like a great, flat, gaily-painted plate. Houses, trees and 

 people, although of different sizes, and the sky with them, 

 lay all in the same plane, and seemed to hang free in space. 



Only by degrees did they separate from one another, 

 and the extended, which connected them together, moved 

 back to the outermost limits of space. The explanation of 

 this was that my glance, passing from the nearer objects to 

 the more remote, was hampered within the space of accom- 

 modation through perpetual re-focussing by the muscles of 

 accommodation, and when it had to deal with more distant 

 objects, seemed, thanks to their distance-signs, to come up 

 against fresh resistance. 



