Wer heilt hat recht

This is a German quote – frequently used in the context of alternative medicine – “who heals is right”. The history of this old quotation is unclear; maybe it is a modification of the Latin “extra ecclesiam salus non est” .
In todays English it is “the doctor’s always right” (or “might is right”?)
Anyway it is nonsense as (1) a healer wants to be successful and not rightful (2) healing (at least on a few occasions) is no proof for the right treatment