158 MYSTICISM AND LOGIC 



data. Of these two classes of inferred entities, the first 

 will probably be allowed to pass unchallenged. It would 

 give me the greatest satisfaction to be able to dispense 

 with it, and thus establish physics upon a solipsistic 

 basis ; but those ^and I fear they are the majority ^in 

 whom the human affections are stronger than the desire 

 for logical economy, will, no doubt, not share my desire 

 to render solipsism scientifically satisfactory. The second 

 class of inferred entities raises much more serious ques- 

 tions. It may be thought monstrous to maintain that a 

 thing can present any appearance at aU in a place where 

 no sense organs and nervous structure exist through which 

 it could appear. I do not myself feel the monstrosity ; 

 nevertheless I should regard these supposed appearances 

 only in the light of a hypothetical scaffolding, to be used 

 while the edifice of physics is being raised, though 

 possibly capable of being removed as soon as the edifice is 

 completed. These " sensibilia " which are not data to 

 anyone are therefore to be taken rather as an illustrative 

 hypothesis and as an aid in preliminary statement than 

 as a dogmatic part of the philosophy of physics in its 

 final form. 



VII. PRIVATE SPACE AND THE SPACE OF 

 PERSPECTIVES 



We have now to explain the ambiguity in the word 

 " place," and how it comes that two places of different 

 sorts are associated with every sense-datum, namely the 

 place at which it is and the place from which it is per- 

 ceived. The theory to be advocated is closely analogous 

 to Leibniz's monadology, from which it differs chiefly in 

 being less smooth and tidy. 



The first fact to notice is that, so far as can be dis- 

 covered, no sensibile is ever a datum to two people at 



