Boltzmann and Wittgenstein or how pictures became linguistic

Emphasis in historiography of science is naturally placed on the discoverie s and inventions which scientists make and generally less on new methods of doing science, but sometimes the latter can he an important clue to help u s understand the former. For example, while we all acknowledge how great th e contributions of Maxwell, Boltzmann, Planck, and Einstein were to physics from roughly 1870 to 1920, we often overlook the significance of a methodo logical phrase which was popular during that same period, namely, what in G erman was called "Bildtheorie'' or in English "picture theory''. But even b efore we can properly study its significance we have to know what the theor y was, but even this presents problems, since the meaning changed. In fact, this paper is an attempt not only to describe the history of that change f rom Maxwell to Wittgenstein but to study in particular how Boltzmann's conc eption of Bildtheorie seems to have been at least partly incorporated into the approach of Ludwig Wittgenstein.