ON THE PSYCHO-PHYSICAL VIEW OF NATURE. 507 



and thinking self, on sensations, and on their arrange- 

 ment or orderly presentation. The sensations them- ss. 



Localisation 



selves are the substance, the spatial arrangement .f sensa- 

 tions. 



of them the form, of our perception of external 

 things. The question was gradually put more and 

 more clearly, How we come to localise certain of our 

 sensations at definite places in the totality of a spatial 

 arrangement ? Herbart added another important reflec- 

 tion, which really dated from Leibniz. Impressed with 

 the unity of all mental existence, and claiming this as 

 the characteristic property of our inner life, he asked the 

 question, How can the oneness or simplicity of this inner 

 existence, as it were, expand itself without losing its 

 unity, into the orderly variety of a spatial contemplation ? 

 For the purpose of an answer to this question he fixed 

 on the phenomenon of motion. The conception of an 

 orderly arrangement of sensations or things in space is 

 gained in great measure by the aid of definite move- 

 ments of the sensitive organs, which are accompanied 

 by definite sensations of motion e.g., by muscular 

 sensations. 



The first of these two questions may be expressed in 

 the words, Given the subjective form of a space percep- 

 tion, either complete in its geometrical arrangement (the 

 nativistic hypothesis) or gradually acquired in the early 

 moments of our conscious life (the empiric hypothesis), 

 how do we make ourselves familiar with, and at home in, 

 this form of perception ? And secondly, By what special 

 properties or local signs do we localise or place each 

 single sensation in its right and orderly position ? The 

 first is the problem of space construction, the second 



