This paper is an attempt at presenting a convincing reading of the first sentences of PI § 109, especially of its third sentence. There Wittgenstein mentions what he calls "the pneumatic conception of thought", which by Miss Anscombe is translated as "the conception of thought as a gaseous medium". By comparing the relevant sentences with their sources in Wittgenstein's manuscripts and additional parallels it is found that Anscombe's rendering is liable to be misleading. Wittgenstein's notion of "pneuma" is likely to be inspired by a conception of the kind elucidated by Oswald Spengler, for instance, according to whose account pneuma is to be understood as a sort of body (Seelenkörper). If you take this as your central image, the pneumatic conception alluded to in PI § 109 is one which can be tracked down in Wittgenstein's early as well as in his middle-period work. In this remark (PI § 109), Wittgenstein tries to mention both helpful and misleading features of his earlier ways of thinking, and what he now calls the "pneumatic conception" can be seen to be the foil for both sorts of features. The central idea is that the core of language contains a scaffolding of rules whose ("pneumatic") substance is the same as that of our thought. In accordance with this view the logical structure of thought is held to be identical with that of language and reality—a notion which fits parts of the Tractatus as well as parts of the original "grammatical" conception developed in the early 1930ies.