INTRODUCTORY. 13 



ing of words and phrases not outside but within our own mon to ail 5 



internal, 



minds. To each of us his own mind is only accessible peculiar to 



the observ- 



to himself. For every one the object of internal reflec- in s sub J ect < 

 tion and observation is different. If the philosophical 

 thinker addresses his hearers or his readers in terms of 

 language, he invites them to do what he has done i.e., he 

 desires that each of them, for himself alone, should retire 

 into the depths of his own consciousness, into his own 

 inner world. He expects that they will there find some- 

 thing analogous to that which he has seen and found 

 within himself. But the objects are not identical, and 

 that they are, in a greater .or smaller degree, similar, 

 rests upon an assumption which practice has taught us to 

 make and which experience has shown to be justified and 

 useful. Nevertheless the many misunderstandings, the 

 endless controversies, the wearisome discussions which fill 

 philosophical books, show sufficiently that this assumption 

 is only very partially correct. 



If the fact that the object of philosophical inquiry, 

 viz., the inner world, is not the same for all of us, explains 

 one of the great difficulties of philosophical thought, 

 another feature which establishes an important difference 

 between scientific and philosophical reasoning will at 

 once be seen to give to the former an enormous advan- 

 tage over the latter. This difference can be defined by 9. 



.. Outer world 



saying that the outer world exists in space, whereas the in space ; 



inner world 



inner world presents only succession in time. We have in t im e. 

 learnt to apply to things in space the methods of 

 measurement, of exact definition, and of subsequent 

 calculation. The history of scientific thought has shown 

 that science has progressed in the same degree as the 



