Compared to Ernst Mach's influence on the conceptual development of physics, his efforts to popularize science and his reflections on science literacy are known to a much lesser degree. The approach and the impact of Mach's popular scientific lectures are discussed in view of today's problems of understanding science. The key issues of Mach's popular scientific lectures, reconsidered in the light of contemporary science, still hold a high potential in fascinating a general audience. Moreover, Mach's grand theme, the relation of the physical to the psychical, is suited to contribute to a dialogue between different knowledge cultures, e.g. science and humanities.