At one point in his memoir, Daudet describes staying at a sanatorium, one of those places where everyone understands what everyone else is going through. He talks about the strange pleasure of searching for the patient whose experience of illness is most like his own. Today’s version of the sanatorium is the Internet, where you find a vaporous world of fellow-sufferers, companions in isolation and fear and frustration, as well as practitioners who have made it their life’s work to understand why a segment of the population always feels unwell. I fell into the rabbit hole, and emerged in another world, online.