A  covenant  by  a   creditor   with   his   debtor  not  to   sue  him    covemuit

not  to  mtk

for  the  debt  is  not  technically  a  release.  But  since,  if  the  creditor
should  sue,  the  debtor  could  then  in  turn  sue  him  for  a  breach
of  his  covenant  and  recover  back  the  same  sum  which  the  credi-
tor had  just  recovered  from  him,  so  that  the  net  result  of  the
two  actions  would  be  nothing,  the  covenant  is  allowed  to  have
directly  the  force  of  a  release  in  order  to  prevent  the  bringing
of  two  useless  actions  or,  as  it  is  called,  circuity  of  action.
769,  Very   similar   to   a   release   is   an   agreement  by  the  ^^j^^^
parties  to  an  obligation    to  discharge  or  vary  it.      If  the  obliga-   »*«e™«°t-
tion  was  created  by  a  specialty,  it   can    at   law  be  discharged  or  jP^jjJJ^S!
varied  only  by  specialty.     An    unsealed  agreement  to  that  effect,

even  though  in  writing,  has  at  law  no  operation  upon  the  original
obligation,  though  it  may    itself  be    a   valid   contract   for   whose

22  As  to  interest  awarded  bj  way  of  damagesj  aee  2  896.
534  PBIVATE  LAW.
