Canon XV: The Breath Within
Fact (sourced): Chrysippus lived c. 280-207 BCE; no treatise of his survives, and his views come from fragments and later reports (IEP, Chrysippus). Routledge's Stoicism entry says the active body (pneuma) permeates passive matter "through and through", a total blending (krasis), a doctrine attributed to Chrysippus via Diogenes Laertius.
Reconstruction: The picture of pneuma as a continuous cosmic medium is assembled from later testimony. It is not read from a complete original text.
Belief (ours): Aether is outside the world, but pneuma is inside it. Aetherism holds both as one question: what pervades everything?
Sources: iep.utm.edu/chrysippus, rep.routledge.com (Stoicism, the continuum), studyancients.com. Secondary sources only; primary texts unread.