Passage: "Historians of science like to narrate the germ theory's triumph as a clean substitution: miasma theory, which blamed disease on foul air, was refuted by evidence and replaced by the correct doctrine of specific microbial causation. But the substitution was never so tidy, because miasma theory was not simply wrong about the facts it purported to explain. Cholera outbreaks did cluster around foul-smelling, poorly drained districts; the correlation miasmatists observed was real. What they mistook was the mechanism -- they inferred that the smell itself, or the vaguely defined 'bad air' co-located with it, was the causal agent, when in fact both the smell and the disease shared an unremarked common cause: fecally contaminated water supplies bred both the odor and the pathogen. Germ theory did not overturn a body of false observations; it supplied the correct causal architecture linking observations that miasma theory had already correctly, if incompletely, assembled. The lesson is not that discredited theories are typically built on illusions, but that they often correctly detect a pattern while misattributing its source -- a distinction historians of science collapse when they tell the story as sheer replacement rather than reinterpretation."