Advertising is an activity which can be defined in many ways. One definition is of particular interest in the context of this paper. It is a definition which is suggested by more or less simple theories which are used when defining advertising norms and tasks. Although this definition of advertising is not yet explicitly given, it should read roughly as follows: Advertising usually intends to reshape properties of the product in such a way that conformity to cultural norms increases and adoption is facilitated. At first sight this definition seems to be valid only with regard to advertising for new products, but basically the same applies for all products. In those cases where advertising was really successful in putting old-fashioned products on their feet again, it owed its success to a large extent to finding e. g. new applications for the product, or "reshaping" product-properties to make them different and modern. For this reason a general theory of diffusion of innovations is an important feature in modern marketing with a relevance going beyond that of introducing new products alone.