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point of its course may initiate secondary disturbances, 

 reinstating previous feelings, while these again may 

 set up other disturbances ; so that every sensation is 

 seen to be organically connected with an indefinite 

 number of previous sensations. The difficulty, then, 

 will be, not to make some connection, but to select 

 out of the innumerable possible connections those 

 which shall be most useful. This process of selecting 

 and arranging reminiscences in usable connection one 

 with another, is what I have termed syntaxis. 



In the absence of any idea of an organic nexus 

 between different sensations, philosophers had 

 imagined metaphysical connections, constructed, as 

 it were, artificially by an entity which they called 

 The Mind. Hume examined the theory current 

 in his time with regard to one of the principal of 

 these metaphysical connections, namely, causation, 

 and found it, as he said, " irrational." Now, the 

 terms cause and effect are still used very loosely even 

 by the most careful writers, but there is nothing 

 irrational about the meaning of the words in their 

 strict scientific sense. They denote an identity 

 looked at under different aspects, or in different 

 phases. Thus, when the elasticity of a stretched 

 string is said to cause its return towards the position 

 of equilibrium, the potential energy of its displace- 

 ment is looked on as being identical with the kinetic 

 energy of its return, but as exhibited in a different 

 phase. When vibration is said to cause sound, the 



