[6 "non-natural", yet most natural conditions necessary for health]

The medieval preventive medical scheme which persisted up to the period of Enlightenment, called the "Six Things Non-natural and Necessary", comprised six items whose influence on the health of the individual is not inborn (not determined by innateness), but no one can avoid facing them in his life (hence, they are "necessary"); however, they may be tackled in ways either promoting or impairing health (viz.: air, food, exercise, sleep, emotions, cleansing and sexuality). The taxative list of "Six Things" is normalized in book Six of Hippocratic "Epidemics"; later, the topos was furthered by Galen, John of Alexandria (and other Alexandrinian authors) and Hunain ibn Ishaq. At least nine authors in Bohemia, Moravia and Slovakia divulged the "Six Non-natural Necessary Things" from the 15th to the end of the 18th century. Due to the re-evaluation of "naturalness" on the break from Enlightenment to Romantism, the concept of "non-natural" conditions of health was abandoned; during the period of analytical medicine relevant questions were side-tracked; only the "re-synthetical" medicine (in the second half of the 20th c.) restored the original intuitive scheme of "Six Non-natural and Necessary" conditions of health in the new form of the "risk factors of health relevant behaviour".