88

POLITICAL  ECONOMY

on  the  side  of  supply  by  differentiating  the
experiences  of  businesses—their  experiences
as  a  whole—to  use  the  phrase  previously
employed,  just  as  it  is  possible  to  explain
value  on  the  side  of  demand  by  differentiating
the  experiences  of  consumers.
The  necessity  of  taking  experience  as
a  whole  in  our  theorising  may  be  emphasised
again,  now  that  we  deal  with  it  on  the  side
of  supply.  Neither  demand  nor  supply  can
be  atomistically  conceived.  I  do  not  know
the  utility  of  sugar  when  it  is  in  my  cup  of
coffee,  but  I  do  know  the  difference  that  it
makes  to  the  utility  of  the  cup  of  coffee  ;
as  a  producer  of  steel  I  could  not  separate
the  cost  of  a  particular  ton  of  steel  from  the
costs  of  other  tons  of  steel  made  by  me
(because  many  tons  of  steel  are  made  at  a
time  by  groups  of  productive  factors  working
as  a  whole),  but  it  would  be  theoretically
feasible  to  calculate  what  difference  its  production ­
  made  to  my  total  costs.  However,
it  happens,  as  we  have  seen,  that  the  cost
per  unit  of  output  in  a  business  comes  on  to
the  stage  among  the  supply  forces,  and  that,
in  relation  to  the  marginal  business,  when
supplemented  in  the  manner  already  indicated, ­
  it  serves  the  purpose  (the  settlement
of  supply  prices)  which  would  be  served  in  a