Along  with  diversities  in  their  shapes  and  composi-
tions go  diversities  in  the  actions  they  perform:  they
grow  into  unlike  organs  having  unlike  duties.  As-
suming the  entire  function  of  absorbing  nutriment
at  the  same  time  that  it  takes  on  its  structural  char-
acters, the  alimentary  system  becomes  gradually
marked  off  into  contrasted  portions:  each  of  which
has  a  special  function  forming  part  of  the  general
function.  A  limb,  instrumental  to  locomotion  or
prehension,  acquires  divisions  and  sub-divisions
which  perform  their  leading  and  their  subsidiary
shares  in  this  office.  So  is  it  with  the  parts  into  which
a  society  divides.  A  dominant  class  arising  does  not
simply  become  unlike  the  rest,  but  assumes  control
over  the  rest;  and  when  this  class  separates  into  the
more  and  the  less  dominant,  these,  again,  begin  to
discharge  distinct  parts  of  the  entire  control.  With
the  classes  whose  actions  are  controlled  it  is  the
same.  The  various  groups  into  which  they  fall  have
various  occupations:    each  of  such  groups   also,


Herbert  Spencer:  The  Nature  of  Society


141


within  itself,  acquiring  minor  contrasts  of  parts
along  with  minor  contrasts  of  duties.
And  here  we  see  more  clearly  how  the  two  classes
of  things  we  are  comparing,  distinguish  themselves
from  things  of  other  classes;  for  such  differences  of
structure  as  slowly  arise  in  inorganic  aggregates,
are  not  accompanied  by  what  we  can  fairly  call  dif-
ferences of  function.
217.  Why  in  a  body  politic  and  in  a  living  body,
these  unlike  actions  of  unlike  parts  are  properly  re-
garded by  us  as  functions,  while  we  cannot  so  regard
the  unlike  actions  of  unlike  parts  in  an  inorganic
body,  we  shall  perceive  on  turning  to  the  next  and
most  distinctive  common  trait.
