One of my favourite historical phenomena is technology that’s based on a totally off-the-wall theory about how the world works, but ends up being sort of effective because it’s close enough. Like those old-timey plague doctor masks, whose enormous beaks are an enclosed breathing apparatus stuffed full of dried aromatic herbs on the theory that disease is communicated by the odour of decay – which is completely wrong, of course, but the masks ended up being reasonable effective at their purpose anyway because it turns out that sticking a big wad of dried plant matter in front of your airway is a pretty effective way to avoid inhaling aerosolised bodily fluids.

My favorite is the fact that scurvy was cured, and then un-cured because a bunch of perfectly sensible and intelligent people didn’t know what a vitamin was.