During medieval times what was widely believed to control the health

Well there were many theories back then as to what causes sickness or health however one of the main theory's was one which involved the elements. You see, many mid evil doctors thought that having too much of one of the four main elements could lead to sickness. For instance, lets say you had a fever. The doctor would say that you have to much fire in you and you should take a cold bath to get your frost elements up. I know by today's standards it sounds crazy but thats what they believed back then.