 To sum up this discussion of Boltzmann’s answer to the reversibility objection: it seems that on all above readings of his two 1877 papers, the lacuna between what Boltzmann had achieved and what he needed to do to answer Loschmidt satisfactorily – i.e. to address the issue of the evolution of distributions of state and to prove that non-uniform distributions tend, in some statistical sense, to uniform ones, or to prove any other reformulation of the H-theorem – remains striking.