Surprised no mention of "the doctrine of signatures" pace Pratchett which I believed was a real "thing" Separatly mouldy bread on wounds could have been observ

Surprised no mention of "the doctrine of signatures" pace Pratchett which I believed was a real "thing" Separatly mouldy bread on wounds could have been observational to evident effect or simply mumbo jumbo. Surgery sometimes worked. People survived occasionally.