SENSE-DATA AND PHYSICS 165 



the appearance of a thing in a given perspective is 

 causally affected by the matter between the thing and the 

 perspective. We have found a meaning for &quot; between a 

 thing and a perspective.&quot; But we want matter to be 

 something other than the whole class of appearances of a 

 thing, in order to state the influence of matter on appear 

 ances. 



We commonly assume that the information we get 

 about a thing is more accurate when the thing is nearer. 

 Far off, we see it is a man ; then we see it is Jones ; then 

 we see he is smiling. Complete accuracy would only be 

 attainable as a limit : if the appearances of Jones as we 

 approach him tend towards a limit, that limit may be 

 taken to be what Jones really is. It is obvious that from 

 the point of view of physics the appearances of a thing 

 close to &quot; count &quot; more than the appearances far off. We 

 may therefore set up the following tentative definition : 



The matter of a given thing is the limit of its appear 

 ances as their distance from the thing diminishes. 



It seems probable that there is something in this 

 definition, but it is not quite satisfactory, because em 

 pirically there is no such limit to be obtained from sense- 

 data. The definition will have to be eked out by con 

 structions and definitions. But probably it suggests the 

 right direction in which to look. 



We are now in a position to understand in outline the 

 reverse journey from matter to sense-data which is per 

 formed by physics. The appearance of a thing in a given 

 perspective is a function of the matter composing the 

 thing and of the intervening matter. The appearance of 

 a thing is altered by intervening smoke or mist, by blue 

 spectacles or by alterations in the sense-organs or nerves 

 of the percipient (which also must be reckoned as part of 

 the intervening medium). The nearer we approach to 



