viewing genre as a rhetorical device gives the author and the reader more freedom and "allows for choices." Genres are not free-standing entities, but are actually intimately connected and interactive amongst themselves and the activities carried out by those among whom the genres circulate, leading to pervasive change and hybridity. Rhetorical theory of genre recognizes that genres are generated by authors, readers, publishers, and the entire array of social forces that act upon a work at every stage of its production. Consequently rhetorical genre scholars tend to focus on the processes of genre production and change rather than taxonomies of genre that are mutable and subject to the changing interests and perceptions of users within evolving social circumstances. This recognition of the mutability and fluidity does not make the taxonomy of texts easy. Chandler points out that very few works have all the characteristics of the genre in which they participate. Also, due to the interrelatedness of genres, none of them is clearly defined at the edges, but rather fade into one another. Genre works to promote organization, but there is no absolute way to classify works, and thus genre is still problematic and its theory still evolving. Moreover, the metagenre as a concept has been an important point to study. According to Giltrow, metagenre is "situated language about situated language". Metagenres such as institutional guidelines can be "ruling out certain kinds of expression, endorsing others", constraining and enabling. The concept of metagenre also provides a valuable way to understand the dynamics of institutional interrelations between genres. In the mental health discourse, for example, has been demonstrated the metageneric function of the American Psychiatric Association's (DSM) for standardizing and mediating the localized epistemological communicative practices of psychiatrists. Functions and limits Genre began as an absolute classification system in ancient Greece. Poetry, prose and performance had a specific and calculated style that related to the theme of the story. Speech patterns for comedy would not be appropriate for tragedy, and even actors were restricted to their genre under the assumption that a type of person could tell one type of story best. This classical system worked well as long as the arts were largely directed by nobility and rich patrons. A common understanding of meaning was handy in knowing what the employer expected, and the crowds understood it. During the Enlightenment period in 18th century Europe, this system of patronage began