  The Ehrenfests' reconstruction of Boltzmann's work thus gave a prominent role to the ergodic hypothesis, suggesting that it played a fundamental and lasting role in his thinking. Although this view indeed produces a more coherent view of his multifaceted work, it is certainly not historically correct. Boltzmann himself also had grave doubts about this hypothesis, and expressly avoided it whenever he could, in particular in his two great papers of 1872 and 1877b. Since the Ehrenfests, many other authors have presented accounts of Boltzmann's work. Particularly important are Klein (1973) and Brush (1976). Still, much confusion remains about what exactly his approach to statistical physics was, and how it developed. For a more elaborate attempt to sketch the general landscape, and Boltzmann's work in particular,I refer to (Uffink 2007). 