The first group we look at are the authors of the works. Over time this interest-group also came to include inventors, playwrights, actors, artists, film-makers and performers. They are usually considered to be uniquely creative, or inventive, creating something which would have not been there without their efforts.
The idea of an author, however, has been criticized, both from non-western and post-modern perspectives. The non-western camp points to shared cultural heritage such as folk-stories, which cannot be ascribed to single authors, and which come to be through re-tellings in ever slightly better variations. And even in medieval Europe it was very uncommon for artists to claim authorship of their works. In those times God, a people, a tradition, or a profession were identified as the source of the creativity. Post-modern critique of the concept of the author is similar in that it views texts as shaped or even produced by the discourses (conversations, other texts) in which they are embedded. It sees the 'author' as an invention of 18th century Romanticism, as a `Privileged moment of individuality'.
While acknowledging the sensibility of this critique, it is so that even if authors would live with illusionary identities, there still is labour involved in creation, or an efficient cause in more philosophical terms. It takes time to create or transform something, and no matter how much it is reduced because of all the other texts and facilities one can draw from, there always is a cost involved in terms of time. Professional authors can thus at least be identified as a group because of their similar set of interests, namely: some form of income or pay for their work; access to the cultural heritage as input for new works; and attribution and recognition by others.