The modern sauna has retained a strong element of ritual, but little of the mystic reverence once conferred on it remains. Until the 19th century the sauna was still a hospital and a maternity ward as well as a bathing room. Etiquette required social restraint, if not complete silence while bathing. Connected with birth and health and life-affirming water, the sauna was as sacred as a church. Even today, the notion persists that the sauna can in some way purge the blood.
Opinions vary on the tangible medical benefits.
But all agree that sweating is a desirable inbuilt mechanism for keeping the body temperature as close as possible to 37 degrees Centigrade and that it helps to expel wastes. There' s a consensus, too, that the feeling of relaxation that is the intended outcome is of spiritual, and therefore medical, advantage. The placebo effect of the sauna is powerful and only the faintest of heart, in either physical or mental sense, need approach with caution. Ideally, the sauna should be as close to the water as possible - sea, lake or river, it doesn't matter which. The sauna should be heated with a wood fire.