DEMAND

59

good  enough  to  get  employment  is  called  the
marginal  workman  or  the  workman  of  marginal
quality.  Also  the  employer  in  an  industry
whose  capacity  only  just  attains  the  level
which  enables  him  to  make  a  living  in  the
industry  is  the  employer  of  marginal  quality.
It  is  exceedingly  important  that  the  distinction ­
  between  these  two  uses  of  marginal  should
be  firmly  grasped.
We  are  now  adequately  equipped  to  define
wealth  and  value.  Broadly  understood  all
that  people  want  is  wealth.  But  sometimes
the  conception  is  narrowed  to  exclude  things
that  are  accessible  to  all  and  unlimited  in
quantity  such  as  air  ;  and  sometimes  in
addition  the  qualification  is  introduced  that
desirable  things  to  be  wealth  must  have
been  produced  by  labour.  Value  may  mean
value  in  use  or  value  in  exchange.  By  the
former  is  meant  the  utility,  as  above  defined,
of  things  that  are  wanted  ;  and  by  the  latter
is  meant  the  quantity  of  other  things  that
the  thing  in  question  will  exchange  for.  The
value  in  exchange  of  an  article  or  service  is
evidently  dependent  upon  its  marginal  utility
to  would-be  purchasers  and  the  marginal
utilities  of  the  things  offered  for  it.  When
what  is  offered  is  money,  value  in  exchange  is