150 MYSTICISM AND LOGIC 



this statement " matter," " view from a given place," 

 ' appearance," " intervening medium " will all be de- 

 fined in the course of the present paper.) We have not 

 the means of ascertaining how things appear from places 

 not surrounded by brain and nerves and sense-organs, 

 because we cannot leave the body ; but continuity 

 makes it not unreasonable to suppose that they present 

 some appearance at such places. Any such appearance 

 would be included among sensibilia. If j>er impossibile 

 there were a complete human body with no mind in- 

 side it, all those sensibilia would exist, in relation to that 

 body, which would be sense-data if there were a mind in 

 the body. What the mind adds to sensibilia, in fact, is 

 merely awareness : everything else is physical or physio- 

 logical. 



IV. SENSE-DATA ARE PHYSICAL 



Before discussing this question it will be well to define 

 the sense in which the terms " mental " and " physical ' 

 are to be used. The word " physical," in all preliminary 

 discussions, is to be understood as meaning ' what is 

 dealt with by physics." Physics, it is plain, tells us some- 

 thing about some of the constituents of the actual world ; 

 what these constituents are may be doubtful, but it is 

 they that are to be called physical, whatever their nature 

 may prove to be. 



The definition of the term " mental " is more difficult, 

 and can only be satisfactorily given after many difficult 

 controversies have been discussed and decided. For 

 present purposes therefore I must content myself with 

 assuming a dogmatic answer to these controversies. I 

 sliall call a particular " mental " when it is aware of 

 something, and I shall call a fact " mental ' when it 

 Contains a mental particular as a constituent. 



