Until 1973, the name on a pack of Persil, Henkel’s laundry detergent, normally came with a year. In 1973, Henkel dropped the year from the pack. The new advertisements carried a new slogan instead: Persil. Da weiß man, was man hat. (Persil. You know what you have.) Henkel’s own history says that this line stayed in consumers’ memory for good.