How comes, in fact, against any marketing rule, that centennial brands are are in great shape, and that young brands that we thought promised to a bright future die before 20 years? Around Georges Lewi, renowned specialist of "mythical brands", we will try to understand with about ten brands the reasons for their longevity, or better, for some of them, of their spectacular rebound. Is the life cycle of the brands so different from the product one that can be schematized in birth, development and final death? What is the unit of time to assess the youth or topic of a brand: buzz ? year ?, generation ? or human memory ? How to explain the rebirth of a brand that don’t sell anymore ? How did some people manage this feat ? Is this really a masterstroke ? Which manager profile is likely to achieve this feat? Why do others with, apparently, the same professional assets fail? Is the life cycle of a brand part of these "black holes" partly still unexplained?