492 SCIENTIFIC THOUGHT. 



little influence over the Berlin school of physiology, but 

 it has had a considerable influence on several members of 

 the Leipzig school. In this school Lotze was educated. 



Locke had taught, and his followers had accepted, the 

 doctrine that the so-called secondary qualities of sensible 

 things, such as colour, sound, hardness, &c., were sub- 

 jective. Speculative physics had prepared this view by 

 translating such properties into special forms of aggrega- 

 tion or periodic motion, leaving only extension and re- 

 sistance as the primary properties inherent in things. 

 Kant had gone a step further, and maintained that 

 space and time were likewise only subjective forms of 

 our perceiving sense apparatus. Two problems grew out 

 of this view, which are not clearly stated in Kant's 

 writings. First, How does the perceiving mind arrive 

 at the elaborate and systematic space conception which 

 is peculiar to us human beings ? — i.e., out of what per- 

 ceptive elements, and by what psychical processes, is it 

 gradually built up ? Secondly — What is it that locates 

 our sensations at definite places in space ? There is a 

 third question which Kant put and answered, that re- 

 ferring to the nature and validity of the geometrical 

 axioms. According to his view the axioms of geometry 

 are innate, expressive of the inborn nature of our space 

 conceptions ; in fact, the truths of geometry formed in 

 his view the only instance of knowledge gained not by 

 experience but a jpriori — before or outside of experience. 

 18. An entirely independent series of psycho-physical in- 



The brothers . . i n t i 



Weber. vcstigations was started even before Johannes Mliller, 

 by Ernst Heinrich Weber of Leipzig, who, with his two 

 brothers, Wilhelm and Eduard, may be considered as 



