■i-  t

32  POLITICAL  ECONOMY
The  long-period  result  may  be  overlaid,  so
to  speak,  as  the  surface  of  the  sea  is  by
waves  ;  but  even  when  storm  waves  make
the  ocean  a  tumult  tides  still  rise  and  fall.
Finally,  it  is  to  be  remarked  that  the
tendencies  to  be  studied  are  measurable,  and,
indeed,  are  actually  measured  in  the  course
of  our  every-day  doings,  in  terms  of  money.
Owing  to  this,  more  precise  generalisations
can  be  laid  down  than  would  be  possible
otherwise.