182

POLITICAL  ECONOMY

using  machines  and  tilling  the  ground,  and
so  forth,  that  the  real  income  of  the  community ­
  is  maximised.  When  we  say  that
the  marginal  utility  of  capital  is  a  certain
amount—which  means  that  interest  must
be  that  amount—we  mean  that  the  employment ­
  of  another  increment  of  capital  (i.e.,
the  employment  of  a  little  more  labour  in
making  machines  and  so  forth)  would  raise
the  net  income  of  the  community  by  that
amount.  That  is  to  say,  there  will  be  a  net
gain  from  employing  more  capital  so  long
as  the  marginal  utility  of  capital  is  above
zero.  Why,  then,  is  not  capital  applied  to
production  until  interest  drops  to  zero  ?
The  answer  cannot  be  given  in  a  single
sentence.  In  the  first  place,  sacrifice  must
be  made  in  the  form  of  deferment  of  consumption, ­
  or  saving,  some  time  before  the
reward  is  reaped,  and  the  share  of  this  sacrifice
which  fell  to  the  poorer  classes  might  be
quite  beyond  their  saving  powers.  Robinson
Crusoe  could  not  have  made  all  at  once
every  kind  of  instrumental  capital  that  he
needed.  He  had  to  calculate  the  time  he
could  spare  from  rest,  recreation  and  the  work
which  was  more  immediately  productive  of
what  he  wanted  to  live.  In  the  second
place,  the  providence  of  many  people  is