460 PSYCHOLOGY. 



That is, we do not care whether there be any real sameness 

 in things or not, or whether the mind be true or false in its 

 assumptions of it. Our principle only lays it down that 

 the mind makes continual use of the notion of sameness, 

 and if deprived of it, would have a different structure from 

 what it has. In a word, the principle that the mind can 

 mean the Same is true of its meanings, but not necessarily 

 of aught besides.* The mind must conceive as possible 

 that the Same should be before it, for our experience to be 

 the sort of thing it is. Without the psychological sense of 

 identity, sameness might rain down upon us from the outer 

 world for ever and we be none the wiser. With the psy- 

 chological sense, on the other hand, the outer world might 

 be an unbroken liux, and yet we should perceive a repeated 

 experience. Even now, the world may be a place in which 

 the same thing never did and never will come twice. The 

 thing we mean to point at may change from top to bottom 

 and we be ignorant of the fact. But in our meaning itself 

 we are not deceived ; our intention is to think of the same. 

 The name which I have given to the principle, in calling it 

 the law of constancy in our meanings, accentuates its sub- 

 jective character, and justifies us in laying it down as the 

 most important of all the features of our mental structure. 

 Not all psychic life need be assumed to have the sense 

 of sameness developed in this way. In the consciousness 

 of worms and polyps, though the same realities may fre- 

 quently impress it, the feeling of sameness may seldom 

 emerge. We, however, running back and forth, like spiders 

 on the web they weave, feel ourselves to be working over 

 identical materials and thinking them in different ways. 

 And the man who identifies the materials most is held to 

 have the most philosophic human mind. 



* There are two other ' principles of identity ' in philosophy. The 

 ontological one asserts that every real thing is what it is, that a is a, and b, 

 b. The logical one says that what is once true of the subject of a judgment 

 is always true of that subject. The ontological law is a tautological 

 truism;' the logical principle is already more, for it implies subjects unal- 

 terable by time. The psychological law also implies facts which might not 

 be realized : there might be no succession of thoiights; or if there were, the 

 later ones might not think of the earlier; or if they did, they might not 

 recall the content thereof; or, recalling the content, they might not take it 

 as ' the same ' with anything else. 



