20

POLITICAL  ECONOMY

an  all-embracing  theory.  The  method  developed ­
  by  Dr.  Marshall  may  be  called  the
marginal  method  ;  and  associated  with  it  in
the  most  convincing  modern  speculations  is
the  conception  of  individual  experience,  and
even  of  society,  as  an  organic  whole.  The  two
chief  notions  in  economic  theory  to-day  consist
in  seeing  each  item  of  experience  as  in  continuous ­
  relation  with  the  rest  of  experience,  and
in  explaining  the  definite  results  reached  in
economic  affairs—the  consequences  of  demand
and  supply,  to  use  the  expression  sanctified
by  long  usage—as  largely  brought  about  by
the  differences  made  to  the  totality  of  experience ­
  by  the  final  activities  of  producing  and
consuming.  It  is  difficult  to  expound  these
notions  in  brief,  but  their  import  will  be
brought  out  in  each  of  the  succeeding  chapters
of  this  book.  On  completing  his  perusal  of
what  follows,  the  reader  who  returns  again
to  this  page  will  see  on  the  instant  what  its
vague  phrases  mean.  In  the  technical  language ­
  of  mathematics  the  chief  part  of  the
explanation  of  economic  value,  whether
revealed  in  the  prices  of  goods  or  the  rates
of  international  exchange,  or  the  level  of
wages  or  the  amount  of  interest,  is  to  be  found
in  the  differentiation  of  economic  experience
—in  observing  the  differences  made  to  the