  Even today, commentators on Boltzmann's works are divided in their opinion. Some praise them as brilliant and exceptionally clear. Often one finds passages suggesting he possessed all the right answers all along the way — or at least in his later writings, while his critics were simply prejudiced, confused or misguided (von Plato, Lebowitz, Kac, Bricmont, Goldstein). Others (Ehrenfests, Klein, Truesdell) have emphasized that Boltzmann's work is not always clear and that he often failed to indicate crucial assumptions or important changes in his position, while friendly critics helped him in clarifying and developing his views.