Heredity of the Memory. 49 



ever this reproduction occurs the tendency is thereby strengthened ; 

 so that a tendency often reproduced becomes almost automatic. 

 We might go somewhat further, and say that the relation subsisting 

 between the actual perception and the residuum is the relation 

 between the conscious and the unconscious. In the perception or 

 the idea the consciousness perishes ; or, more accurately, there 

 takes place a transformation, of which we can have no precise idea, 

 but which must be very analogous to the transformations of the 

 physical world (heat into motion, motion in light, etc.). Between 

 these two worlds of consciousness and unconsciousness, there 

 must exist such a correlation that to each mode of the one a mode 

 of the other corresponds. Mental life is a constant transformation, 

 the unconscious becoming conscious, and vice versa; but this 

 transformation does not take place by chance : though the laws are 

 unknown, it is not without laws. If we could say which form of 

 the unconscious corresponds to each form of consciousness, we 

 could say what relation subsists between a perception or an idea 

 and its residuum. 



This we cannot do. Herbart, and after him Miiller, the 

 physiologist, supposed they made some advance in the explana- 

 tion of the phenomena by comparing ideas to forces which have 

 their statics and dynamics. But, in the first place, it may be 

 remarked that consciousness is one, and that therefore it can 

 at each instant hold only one idea. Its form is that of a simple 

 series ; and though certain states of consciousness seem to be 

 simultaneous, they are, in fact, successive. It we try to think 

 simultaneously cf a lion and a mountain, a cube and a sphere, 

 it will be seen that one idea excludes the other, and that we can 

 think of them only successively or alternately. From this it 

 follows i- 

 That an idea which occupies the consciousness can be displaced 

 only by a stronger idea. If the two mental forces which contend 

 for the occupation of the consciousness are alike, and act in one 

 direction, the result is a very intense state of consciousness. If the 

 two forces are equal and contrary, they will be in equilibrium. 

 If they are unequal and contrary, the one will over-master the 

 other, but in doing so loses a part of its own force equivalent 

 to that which it displaces. This is proved by the fact that an 



