OF NATURE. 571 



This knowledge, however, though extensive, remained 

 more or less fragmentary and purely illustrative. The 

 unification which was attempted, but never carried out, 

 consisted largely in a monotonous iteration of the terms 

 Matter and Force which were never defined, and in an 

 equally vague reference to Nature and the Laws of 

 Nature, which the reader could hardly help regarding as 

 active principles. The desire w^hich is always felt in such 

 discussions to collect the many statements, illustrations, 

 and analogies into a comprehensive view, led involuntarily 

 to the use of sucli words as Nature, Causality, Natural 

 Laws, &c., in a way similar to that in which the older 

 philosophy of Nature had used the terms Mind, the 

 Absolute, &c., without clearly defining them. 



In a former chapter which treated of the problem of 

 the Inner World, I endeavoured to show how psychology, 

 in its recent developments, has gradually eliminated the 

 word Soul as a conception which was not useful in a 

 methodical treatment of mental phenomena. Neverthe- 

 less the word Soul and its various synonyms have 

 remained indispensable in general language and litera- 

 ture. In a similar manner natural philosophy con- 

 tinually uses such words as Nature, though, for scientific 

 purposes, the idea of nature as a whole vanishes as a 

 superfluous conception. The essence, reality, and unity 

 of natural phenomena are as little explained or defined 

 in natural science as the essence and reality of mental 

 phenomena are discussed in many modern treatises on 

 psychology. In both cases, conceptions such as Soul or 

 Nature lurk in the background as personified agencies 



