SCIENCE AND NATURE 17 



the position is intensified because all our habitual language 

 is based on the assumption that there is an external 

 world which we perceive. For instance, when I want 

 to call attention to the sensation of sound, I can only say 

 that " I hear a noise " ; but the very form of the words 

 which have to be used to convey my meaning imply that 

 the "noise" is something different from the "I," who 

 hears it. Nevertheless it is necessary to try to under- 



<1 how such doubts can be put forward. 



They are based on the fact that the experience of 



seeing an object or hearing a sound is an event which 



- place in my mind ; it is a kind of thought if we 



use the word " thought " to mean anything that goes 



on in my mind. That fact is expressed when it is said 



I" hear the noise. Though the noise may be the 



same, the fact that " I " hear it is different from the fact 



ou " hear it ; the first fact is something that 



happens in ' ' my" mind, the second something that happens 



: " mind. The noise, or the thing that causes the 



, may be something in the world of nature, external 



to both you and me ; but the hearing of the noise, which 



is the fact on which you and I base the conclusion that 



there is a noise or that there is an external object making 



a noise, that hearing is not something external ; it is 



something internal to you or to me, according as you or 



ir it. 'I , that the perception of an external 



object is something internal to the person who perceives 



it of the common-sense attitude towards 



r a> the- view that the perception gives evidence 



rnal obj 



But no\\- we may argue thus. It is agreed Hint the 

 pern i an external object is something intern 



the thoughts, or the m 

 ie perceiver. On the othT li;ml we do not 

 regard a. of a perceiv- dence of 



an external world ; thoughts whirl. 



