Exposing the sick

Their sick they [those from Bastetania] expose upon the highways, in the same way as the Egyptians did anciently, in the hope that some one who has experienced the malady may be able to give them advice.

(Strabo: Geography, Book 3)

They [the Babylonians] bring their sick into the town square, since they do not use doctors. Each invalid is then approached and given advice by passerby who have either suffered from the same sort of ailment themselves or know someone else who has... These prescribe what they did to recover or what they know others did who recovered. You are not allowed to go by a sick person without asking what's the matter with him.

(Herodotus, quoted in Lionel Casson's Travel in the Ancient World)

When you are sick, people are always more than eager to share with you what treatment, recipe, or strange procedure cured them from the same ailment you are presently suffering. The ancient custom of exposing the sick exploits that compulsion, in lieu of professional medical advice that may not be available.

Apparently, in the Leon province of Spain sick people were still being exposed at the beginning of the past century. Or so says a footnote in my copy of Strabo.