We  have  above  seen  that  an  issue  of  fact  arises  only  upon  a
material  allegation  of  the  complaint  controverted  by  the  answer,
and  in  this  case  the  legality  of  the  sale  is  not  alleged,  and  of
course  is  not  and  could  not  be  denied  or  controverted.  Nor  is
such  an  allegation  necessary,  for  it  is  a  well  established  rule  of
pleading  that  it  is  not  necessary  to  allege  what  the  law  will  pre-
sume, and  everything  is  presumed  to  have  been  legally  done
until  the  contrary  is  proved.  1  Chitty  PI.  221 ;  Maynard  v.  Tol-
cott,  11  Barb.  569 ;  Steph.  PI.  353-54 ;  1  Van  Sant.  PI.  330.  But
even  if  it  was  admitted  that  the  defendant  might  by  a  mere
denial  raise  an  issue  on  a  fact  not  specifically  alleged,  yet  the
legality  of  the  sale  is  not  a  traversable  fact  but  a  conclusion  or
inference  of  law.  1  Chitty  PI.  213-14,  540 ;  Ensign  v.  Sherman,
13  How.  Pr.  R.  35;  Mann  v.  More  wood,  5  Sandf.  564;  Lienan
v.  Lincoln,  2  Duer  670;  Lawrence  v.  Wright,  id.  673;  Moss  v.
Sec.  2.]  New  Matter.  545

Riddle,  5  Cranch  351 ;  Major  v.  The  State,  8  Blackf.  72.  And  a
traverse  or  denial  can  only  be  of  matter  of  fact  and  not  of  con-
clusion of  law.  1  Chitty  PI.  612;  Steph.  PI.  191;  1  Barb.  Ch.
Pr.  133;  Comp.  Stat.  541;  Moss  v.  Riddle,  and  Major  v.  The
State,  above.
The  true  object  of  pleading  is  and  always  has  been  to  apprise
the  adverse  party  of  the  ground  of  action  or  defense,  in  order
that  he  may  be  prepared  to  contest  it,  and  may  not  be  taken  by
surprise.  1  Chitty  PI.  478,  213;  Mann  v.  Morewood,  5  Sandf.
