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 '* between a 

 thing and a perspective." 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 " count " 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 



