178 NATURE OF CAPITAL AND INCOME [Car X

   
 

understand any one without having had at least some
view of both of the others.

    
 
 
 
 
 
 
   
  
 
 
 
 
 
   
 
  
  
  
 
  
  
  

§9
Having completed our survey of the summation of the
elements of income, we may properly pause to classify these
items. They fall naturally into three groups. The first
group includes those items of income which are positive
and not negative, that is, the agreeable experiences of subjective
 income, for these, as we have seen, are the only
final uncanceled positive items. The second group includes
 items which are negative but not positive, namely,
disagreeable psychical experiences, and consists of two
classes: (1) the labor and trouble which are sacrificed for
the sake of procuring income through objective channels,
in other words, the toil of the producer; and (2) the disagreeable
 impressions produced in one’s consciousness by an
abnormal state of the body, as aches, pains, and all sorts
of illness, but which are not, like toil, voluntarily incurred
for the sake of future return. The third group includes
what we have called interactions, or items which are at
once positive and negative, according to the point of view.
Both of the first two groups are entirely subjective, and
the last is entirely objective. The third group, interactions,
 constitutes by far the bulk of the items entering
into income accounts, and includes all of those which
enter into practical bookkeeping. It may be subdivided
into two groups: (1) interactions outside of the human
body, and (2) interactions between external wealth and
the human body, or what have been called “final objective
 services.” The following scheme shows further subdivisions:
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