  Meixner's historical remark in 1969 "... it can be shown that the concept of
entropy in the absence of equilibrium is in fact not only questionable but that
it cannot even be defined...." is investigated from today's insight. Several
statements --such as the three laws of phenomenological thermodynamics, the
embedding theorem and the adiabatical uniqueness-- are used to get rid of
non-equilibrium entropy as a primitive concept. In this framework, Clausius
inequality of open systems can be derived by use of the defining inequalities
which establish the non-equilibrium quantities contact temperature and
non-equilibrium molar entropy which allow to describe the interaction between
the Schottky system and its controlling equilibrium environment.
