XXX.] CONSCIOUSNESS AND THOUGHT. 45 



this that I can think of, is that afforded by the use of a 

 geometrical diagram. The lines of the diagram may be either 

 drawn in white chalk on a black board, or in black ink on 

 white paper; but it makes no difference whatever to the 

 geometrical student whether the lines are black or white, 

 nor would it make any if they were red or green. It is 

 necessary that the lines should be of some colour, in order 

 to make an impression on his sight : were there no differ- 

 ence of colour or of shade between the lines and the 

 ground they are drawn on, there would be no sensations 

 with which to begin the consciousness of relations between 

 the lines. But one colour will do as well as another, be- 

 cause his consciousness is not occupied with the colours of 

 the lines and of their ground, or with the relation between 

 them considered as a relation between colours, but with a 

 particular kind of relations, namely relations in space, 

 which are the same for lines of any possible colour, and 

 which constitute the subject-matter of geometrical science. 



I ought to say, that I do not mean to prejudge any 

 metaphysical question as to the nature of geometrical 

 truth. Whatever may be the nature of the tru.ths of 

 geometry in themselves, or in relation to all possible intel- 

 ligence, it is an unquestionable fact that we begin our know- 

 ledge of geometry, and indeed of everything, by cognition 

 of sensations and of the relations between sensations. 



Neither sensation, nor the consciousness of sensation, is 

 thought : the first rudimentary act of thought is the con- 

 sciousness of the relation between sensations. This, I be- 

 lieve, will be admitted by all. But I am inclined to think 

 that it is not strictly accurate to speak of consciousness of 

 relation ; though it is sufficiently accurate not to be 

 misleading up to the present point of the discussion. I am 

 inclined to think that when we say that we are conscious We have 



of the relation between two sensations, we reallv mean ^° ^. 



' - conscions- 



that we are conscious, not of the relations, but of the ness of 



't'pJftfl.fi'i'iQ 



sensations which are related. The relations of geometry ^^ij ^^ ' 



are too abstract to be of much use for illustration here : we related 



T • things. 



must take an example from among what is nearer to mere 



sensation. If I look at a half-open moss rose, I see red 



