456 JAMES CLERK MAXWELL. [CHAP. XIV. 



of no great consequence to the dignity of the Ego, whether 

 this particular object is purely spiritual or has a material 

 substratum, just as history is history, whether or not it has 

 a material substratum of paper and ink. 



Memory is sometimes spoken of as if it were essential 

 to individuality. When I wish to convince myself that I 

 am the same person as a certain baby, I may do so by 

 remembering as my own certain acts done by that baby. 

 It may happen, however, that I cannot ascertain whether 

 my present memory of these acts is due entirely to the 

 direct^impression made by these acts on me, or whether it 

 is not mainly due to. the frequent repetition of the story of 

 these acts, as told to me afterwards by older persons. 



But even if I were to find my memory to be all wrong, 

 and that I am not that baby but a changeling, this would 

 not touch my conviction that I who now am, am one. 



The phenomenon of double consciousness, though not 

 common, seems to be well established. A person has a 

 double series of alternate states. In one the memory, edu- 

 cation, accomplishments, and temper, are quite different from 

 what they are in the other. 



Instances have even been adduced of a man believing 

 himself to be two or even three different individuals at the 

 same time. But when we come to examine any particular 

 case, we find that the man has nothing more than an errone- 

 ous opinion that he is entitled to the position and rights of 

 the King, or of some other person, as well as his own, so 

 that even in his own imagination he is no more than a person 

 who holds several different offices at the same time. 



(2.) The theory of Plastidule souls has been hinted at by 

 several persons of whom Dr. Tyndall has spoken loudest. 

 A much clearer utterance is that of Professor von Nageli, of 

 Munich, in an address delivered at the Munich meeting of 

 the German Association in 1877. 



Du Bois Eeymond, in an address to the same body at 

 Leipzig in 1872, had asserted 



" That in the first trace of pleasure which was felt by 

 one of the simplest beings in the beginning of animal life 



