POLITICAL  ECONOMY

40

12s.,  I  would  buy  two  pounds  ;  if  9s.,  four
pounds  ;  if  6s.,  five  pounds,  and  so  on.  We
therefore  realize  that  there  is  one  almost
universal  law  of  demand,  namely,  that  the
lower  the  price  of  a  thing  which  can  be  bought
in  any  quantity,  large  or  small,  the  more  will
any  person  buy  of  it  if  he  buys  any  at  all.
In  framing  this  law  we  must  be  particular
to  bear  in  mind  that  demand  does  not  indicate
just  a  quantity  of  the  thing  demanded,  nor
just  a  price,  but  on  the  contrary,  many
quantities  and  many  prices,  and  even  more,
namely,  the  relations  between  quantities  and
prices.  And  we  must  be  equally  particular
to  remember  (if  we  care  about  secure  foundations) ­
  what  has  been  said  a  few  pages  back
concerning  utility,  and  bear  in  mind  that
demands  simply  measure  the  ratios  between
preferences.  So  I  should  feel  inclined  to  repeat
my  description  of  demands  as  “quantitative
objective  definitions  of  preferences,”  had
not  one  or  two  critics  opined  that  the  unsophisticated ­
  would  be  unlikely  to  understand  what
the  statement  means.
At  this  point  the  distinction  may  be  drawn
between  private  or  individual  demand  on  the
one  hand  and  public,  collective,  compound  or
market  demand  on  the  other  hand.  The
latter  means  the  demands  of  all  the  people  who