This chapter is devoted mostly to the two volumes of Boltzmann’s Lectures on gas theory, published in 1896 and 1898, with special attention to the novel elements in Boltzmann’s representation of his own contributions and to his silencing of earlier aspects of his theory. Although Boltzmann’s primary intention probably was to improve the diffusion of his own results and to clarify their foundation, he also wanted to give a full, partly historical account of the developments of the theory, including topics to which he had little contributed, such as van der Waals’ theory, and even approaches he had proved to be unsatisfactory, such as Maxwell’s first method for the computation of transport phenomena.