  We argue that the asymptotic condition should not be applied in the
derivation of the real time formalism of thermal field theory. It is shown
that, contrary to popular belief, the generating functional of time ordered
Green functions does not factorise. When no asymptotic condition is applied to
the real time formalism, we find that the normal two component Feynman rules
arises naturally. In addition, the extra Feynman rule that is applied when
calculating vacuum diagrams is simply derived. We also clear up any doubts
regarding the equivalence of the real and imaginary time formalisms. Finally,
we consider these results in the case of the new real time contour.
