52 TIME 



nature of time and so it baffles our comprehension. It 

 is the same paradox which makes us believe we under- 

 stand the nature of an ordinary table whereas the nature 

 of human personality is altogether mysterious. We 

 never have that intimate contact with space and tables 

 which would make us realise how mysterious they are; 

 we have direct knowledge of time and of the human 

 spirit which makes us reject as inadequate that merely 

 symbolic conception of the world which is so often mis- 

 taken for an insight into its nature. 



The Four-Dimensional World. I do not know whether 

 you have been keenly alive to the fact that for some time 

 now we have been immersed in a four-dimensional 

 world. The fourth dimension required no introduction; 

 as soon as we began to consider events it was there. 

 Events obviously have a fourfold order which we can 

 dissect into right or left, behind or in front, above or 

 below, sooner or later — or into many alternative sets of 

 fourfold specification. The fourth dimension is not a 

 difficult conception. It is not difficult to. conceive of 

 events as ordered in four dimensions; it is impossible to 

 conceive them otherwise. The trouble begins when we 

 continue farther along this line of thought, because by 

 long custom we have divided the world of events into 

 three-dimensional sections or instants, and regarded the 

 piling of the instants as something distinct from a 

 dimension. That gives us the usual conception of a 

 three-dimensional world floating in the stream of time. 

 This pampering of a particular dimension is not entirely 

 without foundation; it is our crude appreciation of the 

 absolute separation of space-relations and time-relations 

 by the hour-glass figures. But the crude discrimination 

 has to be replaced by a more accurate discrimination. 



