Volume II of Ernst Kummer's Collected Papers can be divided into four different parts. The first part covers his work on the hypergeometric function, and on repeated integrals of rational functions. In the second part (Algebraic Geometry), we see how the discovery of Kummer surfaces seems to have been an outgrowth of the authors interest in optical properties of biaxial crystals, and in the "cyclides" of Dupin. The relation between Kummer surfaces and quotients of abelian surfaces was discovered only much later. In this section, one also finds a number of papers describing actual plaster models of particular Kummer surfaces with symmetries. The third part is devoted to his work on aerodynamics and ballistics. Finally, the fourth part (Speeches and Reviews) spans a broad range of topics, including a long retrospective on the life and work of Dirichlet.