When did doctors hang a red light outside their doors. I’m rather a student of medical history, and as far as I know they never did, in any place or time I’ve ever heard of. Let’s not forget that electricity and gas lamps are a fairly recent inventions that spread outwards from the cities (and I doubt he claims that doctors used to hang candles inside expensive colored glass cylinders or somesuch.)
No, I’d say that this doesn’t make any sense. A red light would not accord with any symbology I have ever read - and I’ve read a lot. One has to, yo make any sense of the field. For example, the staff of Aesclepius used by the medical profession derived, oddly, from symbol used by publishers (hence it bears the wings of Mercury, god of communications)
Why would doctors use a light, when no other profession did this, and lights don;t ‘just happen’. [Soon after Lyndon Johnson became President in 1963 , he commented on the Rural Electrification Act by noting electricity hadn’t yet reached parts of the hill country in Texas where he’d been born - and that’s in the good ol’ US of A. That may seem a long time ago to you, but I was born then)
I’d want to see a cite before I’d accept that a red light was ever a symbol used by doctors. I don’t believe it ever was.
Now barbers (who were the early surgeons) did hang a striped barber pole out front, in keeping with the practice of many other guilds and professions (e.g. the three balls of the pawnbroker) but itat’s not just red and does nothing to explain the red light.