The task of explaining sight: Helmholtz's writings on vision as a test case for models of science popularization

Studies of Helmholtz's popular lectures on science have concentrated on reconstructing his vision of the scientific enterprise, of its nature, its benefits, and its "civilizing power." This paper offers a different perspective by focusing on Helmholtz's attempts to expose his own scientific work to a wider public. Drawing on recent discussions about how to study science popularization, it analyzes how he made his work on sensory physiology accessible to various audiences. It is argued that the exposition of the theory of vision comprises a complex, multilayered transformation of epistemic messages, which includes the recasting of arguments, recontextualizations, shifting emphasis, and significant changes in style. The popular writings on vision were directed to several different audiences, and, as such, manifest a delicate balance between conflicting agendas. An analysis of the texts indicates that neither the traditional two-step model of science popularization nor the more recent attempt to regard popularization as an "expository continuum" provides appropriate historiographical frameworks to study the popularization of scientific knowledge.