The origins of the sauna are lost in the remote past, associated with purification rituals shared by many ancient religions. Its therapeutic and aesthetic virtues were known in ancient Greece, but it was especially in the Baltic region, and specifically in Finland, that its practice was popularized and perfected as a supreme source of wellbeing. The sauna is simply a bath of very hot, dry air taken in a closed environment in which an appropriate device heats and dehumidifies the air.