130 MYSTICISM AND LOGIC 



in a building, but rather on the analogy of notes in a 

 symphony. The ultimate constituents of a symphony 

 (apart from relations) are the notes, each of which lasts 

 only for a very short time. We may collect together 

 all the notes played by one instrument : these may be 

 regarded as the analogues of the successive particulars 

 which common sense would regard as successive states of 

 one " thing." But the " thing " ought to be regarded as 

 no more " real " or " substantial " than, for example, 

 the role of the trombone. As soon as " things " are con- 

 ceived in this manner it will be found that the difficulties 

 in the way of regarding immediate objects of sense as 

 physical have largely disappeared. 



When people ask, " Is the object of sense mental or 

 physical ? " they seldom have any clear idea either what 

 is meant by " mental " or " physical," or what criteria 

 are to be applied for deciding whether a given entity 

 belongs to one class or the other. I do not know how to 

 give a sharp definition of the word " mental," but some- 

 thing may be done by enumerating occurrences which are 

 indubitably mental : believing, doubting, wishing, willing, 

 being pleased or pained, are certainly mental occurrences ; 

 so are what we may call experiences, seeing, hearing, 

 smelling, perceiving generally. But it does not follow 

 from this that what is seen, what is heard, what is smelt, 

 what is perceived, must be mental. When I see a flash 

 of lightning, my seeing of it is mental, but what I see, 

 although it is not quite the same as what anybody else 

 sees at the same moment, and although it seems very 

 unlike what the physicist would describe as a flash of 

 lightning, is not mental. I maintain, in fact, that if the 

 physicist could describe truly and fully all that occurs in 

 the physical world when there is a flash of lightning, it 

 would contain as a constituent what I see, and also what 



