PHILOSOPHY OF INDUCTIVE INFERENCE. 259 



seem to be always present, and with more or less pro- 

 bability we conclude that when they exist the event will 

 follow. 



Let it be observed that the utmost latitude is at present 

 enjoyed in the use of the term cause. Not only may a 

 cause be an existent thing endowed with powers, as 

 oxygen is the cause of combustion, gunpowder the cause 

 of explosion, but the very absence or removal of a thing 

 may also be a cause. It is quite correct to speak of the 

 dryness of the Egyptian atmosphere, or the absence of 

 moisture, as being the cause of the preservation of 

 mummies, and other remains of antiquity. The cause of 

 a mountain elevation, Ingleborough for instance, is the 

 excavation of the surrounding valleys by denudation. It 

 is not so usual to speak of the existence of a thing at one 

 moment as the cause of its existence at the next, but to 

 me it seems the commonest case of causation which can 

 occur. The cause of motion of a billiard ball may be the 

 stroke of another ball ; and recent philosophy leads us to 

 look upon all motions and changes, as but so many mani- 

 festations of prior existing energy. In all probability 

 there is no creation of energy and no destruction, so that as 

 regards both mechanical and molecular changes, the cause 

 is really the manifestation of existing energy. In the 

 same way I see not why the prior existence of matter is 

 not also a cause as regards its subsequent existence. All 

 science tends to show us that the existence of the universe 

 in a particular state at one moment, is the condition of its 

 existence at the next moment, in an apparently different 

 state. When we analyse the meaning which we can 

 attribute to the word cause, it amounts to the existence of 

 suitable portions of matter endowed with suitable quan- 

 tities of energy. If we may accept Home Tooke's asser- 

 tion, cause has etymologicaUy the meaning of thing before. 

 Though, indeed, the origin of the word is very obscure, its 



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