able   quotations   from  it,  for  instance  in  a  review  of  it  or  in  the
work  of  an  opponent  who  cites  it  for  the  purposes  of  criticism,  or
by  another  person  writing  on  the  same   subject  and  quoting  it  in
support   of  his  views,  is  not  wrongful.     Also  mere  resemblance  is  Merorosem-
not  piracy,  unless  there  is  copying.     Maps  of  the  same  place  and
translations  from  the  same  foreign  work  must  necessarily  resemble
each    other;   and    two    directories  of  the  same  dtv  oli^ht  to  con-
tain  the  same  names  in  the  same  order.     The   rule    here  is  that
each  author  must  resort  to  the  original  sources  of  information  for
himself   and    not     simply   appropriate    the   labors   of    the   other.
Copyright  covers  only  the  form,  not  the  ideas.     Thus  it  has  been  n©  property
held  that  the  inventor  of  a  new  system  of  bookkeeping  could  not,     "
by  copyrighting   the   book   in   which  he  expounded  it,  get  an  ex-
clusive right  in  the  system  so  as  to  prevent  another   person  from
publishing  the  same   system  in  a  diflTerent  book.     He  should  have
patented   it.     An   abridgement  of  a    book,    in   which   the    same  Abridgments.
ideas  are  set  forth  in  the  same  order  but   in    different  and  more
concise  form,    is   not    an   infringement  on  a   copyright,  but  is  an
independent  work  requiring  intellectual  labor  and  judgment.     But
thw  must  be   distinguished   from   a   mere   compilation    made    up
wholly  or  mainly   of  extracts  from  the  original  in  its  very  words
or  substantially  so.     The  translation  of  a  book  is  not  an  infringe-
ment   of  the   copyright,  unless   especially  made    so   by  statute  or
treaty.     A  copyright,  like  a  patent,  has  no  extraterritorial  validity,  international
Bat  international  copyright  is  now  largely  secured  by  treaties  and
statutes.
