For media historians, the "public"(which in Latin languages also means "audience") has been a neglected field despite its importance. They confront three types of obstacle. 1. Epistemological: the notion has been linked to debates of political philosophy and sociology. This involves the need to conceive of a social link that does not involve direct contact (Tarde is central here). In addition, it is difficult to use the notion without being axiological, as the "public"is both a counter-power (against the State) and a new form of tyranny (that of "opinion" or "the majority"). 2. Methodological: one has to reconstitute the audience from a wide range of sources, especially for past audiences never investigated before. Each source tends to create its own public. For the contemporary historian the abundance of sources does not make it easy to match different methods. 3. Material: sources about past audiences are often so rare that one has to conjure up the audiences through an effort of historical imagination that, starting from the abstract and static content of the media, tries to capture the dynamics of reception.