CF is supposed to have appeared about 3,000 BC because of migration of peoples, gene mutations, and new conditions in nourishment. Although the entire clinical spectrum of CF was not recognized until the 1930s, certain aspects of CF were identified much earlier. Indeed, literature from Germany and Switzerland in the 18th century warned ""Wehe dem Kind, das beim Kuß auf die Stirn salzig schmeckt, es ist verhext und muss bald sterben"" or "Woe to the child who tastes salty from a kiss on the brow, for he is cursed and soon must die", recognizing the association between the salt loss in CF and illness.