THE CONCEPTUAL WORLD 41 



in space and time. We remember and classify things 

 and group together all those that seem to resemble 

 €ach other. We form genera, agreeing to ignore all 

 but the most general characteristics of the things which 

 we tr}^ to conceptualise. W^e do not think separately 

 about all the dogs or horses or fishes that we have ever 

 seen, but we group all these animals into species, and 

 it is usually the species that we think about when the 

 idea of a dog or a horse or a herring emerges into our 

 consciousness. When we think about a tramcar we 

 do not think about all the separate vehicles that we 

 have seen, nor about their colours, nor the advertise- 

 ments on the boards outside, nor the people hanging on 

 to the straps inside. Just so much of the experience 

 of what is relevant to the purpose of our thought 

 enters into our idea of the tramcar : it is a conceptual 

 vehicle that we think about. Such is the nature of 

 the concepts that form the basis of our reasoning : 

 they are generalised aspects of our experience of 

 nature, usually poorer in content than were the actually 

 perceived things, except when it is necessary that some 

 individual thing seen or otherwise experienced should 

 be investigated or reasoned about. All our descrip- 

 tions of nature are conceptual schemes. The world 

 of perception, says William James, is too rich to be 

 attended to all at once, but in conceptualising it we 

 spread it out and make it thinner, and we mark out 

 boundaries and division lines in it that do not really 

 exist. It is this generalised nature that is the subject 

 matter of our reasoning of pure science ; and it is 

 these concepts that form the matter of all our descrip- 

 tions. We do not describe nature " as we see it," it 

 is our conceptions that we write about. Genera and 

 species and varieties do not really exist in the animate 

 world : all these are logical categories generated by 



