4 i2 MIND IN EVOLUTION CHAP, xvn 



regarded by the writer as, at best, anything more than a first approxima- 

 tion to the truth. Such as it is, the scheme has a twofold origin : (i) in 

 an analysis of developed experience ; (2) in the observation of less 

 developed experience. The fourfold method of correlation differing stage 

 by stage (a) in respect of the factors explicitly taken into account, and 

 (b) therewith in extent of the sphere comprehended, appears to the writer 

 to be realised in human consciousness as we run the gamut from philo- 

 sophical reflection down to the quasi-mechanical response of habit. 

 Whether these stages into which developed human reason can be analysed 

 correspond to stages by which it grew is of course another question a 

 question only to be answered by a much wider knowledge of animal 

 psychology and of the distinct processes of human development than we 

 at present possess. If we accept evolution, analogy suggests that human 

 intelligence is a specific and higher development of a more general form 

 of intelligence. Hence, if we cut away the higher development, we 

 should come to something roughly common to man and the higher 

 animals. If we cut further, we should come to something common to 

 man and a wider class of animals, and so forth. But there is a caution 

 to be borne in mind. No two species will come to a quite identical de- 

 velopment. No part of the physical structure of man, I suppose, is 

 precisely equivalent to the homologous part in another mammal, still less 

 in another vertebrate of a different class. It is the same with the mental 

 structure. We must not expect to find any animals whose intelligence 

 falls readily into any classification based on the analysis of human ex- 

 perience. We can only expect to find homologous developments. That 

 being understood, it may be said that the method of the preceding 

 chapters, so far as they relate to animals, has been to analyse out the 

 phases of intellectual development as distinguishable in human experience, 

 and to discover what homologous structures are to be found in the animal 

 world. In accordance with these homologies animals are ranked in the 

 classification. 



