reserve m for Cardinal,
  A,B,C for Ordinal,
  x,y,z,X,Y,Z,W for set,
  f for Function;

theorem
  W is Tarski & m in card W implies m in W
proof
  assume
A1: W is Tarski;
  assume m in card W;
  then m in On W by A1,Th9;
  hence thesis by ORDINAL1:def 9;
end;
