INTRODUCTION xxiii 



constitutions generally to the needs of human development 

 which are the conditions of the control that is required. It 

 seemed of secondary importance that there should have 

 been little or no progress in other respects, provided that 

 this essential condition of future advance had been realised. 

 The first object then, as it seemed to me, was to show 

 that mental evolution had in point of fact consisted in a 

 development of consciousness from stage to stage in the , 

 manner supposed. To do this would require a very wide 

 examination on the one hand of animal psychology, on the 

 other of the growth of human thought and of the social 

 customs and traditions in which thought is embodied. But 

 there were also problems of definition and analysis. Con- 

 sciousness and self -consciousness are vague terms. If we 

 are to distinguish phases of their growth accurate criteria 

 are required, and the criteria should be such as are directly 

 reflected in external behaviour. For in the case of animals 

 we have nothing but external behaviour to go by. In the 

 case of man our judgment has to be in large measure 

 indirect, based on the implications of a custom or a belief, 

 or even a phrase. In all cases it was an integral part of 

 the purpose to determine not merely what consciousness 

 was but what it effected. For these reasons I came to take 

 the correlation which is effected in consciousness between 

 different portions of our experience or between different 

 acts and purposes as the basis of a classification. The 

 starting point of this conception is exceedingly simple. If 

 we utter a simple sentence we bring different words, and 

 the words stand for ideas or elements of ideas, into relation. 

 If we execute a purpose we bring a series of acts into rela- 

 tion with one another. It is by correlation that the mind \^ 

 introduces order and establishes its control. There is, 

 however, in organic life a certain degree of correlation 

 apparently independent of consciousness. Thus the several 



