theorem
  for W being Universe, a being Object of Ens(W) st a is terminal ex x
  being set st a = {x}
proof
  let W be Universe, a be Object of Ens(W);
  now
A1: {{}} in W by CLASSES2:56,57;
    assume W = {{}};
    hence contradiction by A1;
  end;
  hence thesis by Th33;
end;
