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POLITICAL  ECONOMY

express  indirectly  the  cost  of  production  of
rides  when  rapidity  of  circulation  is  taken  into
account.  Just  as  the  price  of  a  cab  is  determined ­
  by  such  influences,  so  is  the  price  of  a
piece  of  money.  If  the  money  commodity  be
gold  and  the  unit  be  an  ounce,  the  demand  for
ounces  of  gold  in  relation  to  the  marginal  cost
of  production  per  ounce  of  different  quantities
of  gold  settles  the  value  of  gold  money  ;  but
this  demand  and  supply,  so  long  as  we  confine
our  attention  to  the  monetary  uses  of  gold,
is  derived  from  the  demand  for  exchanging
power  on  the  one  hand,  and  the  supply  of
exchanging  power  associated  with  different
amounts  of  gold  money  on  the  other  hand.
Next,  we  must  take  into  account  the  fact
that  gold  is  not  demanded  merely  for  money
but  also  for  uses  in  the  arts.  The  recognition
of  this  fact  brings  with  it  few  complexities.
It  simply  involves  noting  that  the  demand
for  gold  is  a  composite  demand,  and  that  to
get  the  complete  demand  we  must  add  to  the
demand  for  gold  as  money  the  demand  for
gold  in  the  arts.  Gold  is  by  no  means  peculiar
in  being  the  object  of  a  composite  demand.
Probably  most  demands  are  composite.  Wood,
for  example,  is  demanded  for  buildings,
furniture,  boats,  and  numerous  other  things  ;
and  the  demand  for  wood  is  made  up  of  the