There is a great deal of teen fiction and Christian fiction out there, but is it literature? The answer is not as simple as may seem.
On the extreme end of literature, we have works that practically no one reads through. The prime examples are James Joyce's Ulysses and Finnegan's Wake. At the other extreme take, for instance, Michael Crighton's Airframe, a good, fast read, but with nothing literary about it. In between there are many surprises.
Now, popular literature is that written to sell well, with minimal consideration to character development, themes, or style. Literary novels are character-driven, are elegantly written by some reasonable standard, and deal with themes of universal importance. They often have a subtext and/or symbology. Another characteristic of literary novels is intertextuality, that is, references to other works of literature. For example, Dorothy Sayers' Peter Wimsey novels make frequent allusion, directly or indirectly, to Alice in Wonderland and to Through the Looking-Glass. Most works considered literary display most (though not necessarily all) of these characteristics.
Here's what makes it so difficult to draw a line between literary and popular. No one doubts that Hugo's Les misérables is literary. Yet he was paid by the word and the novel appeared first by installments in newspapers, the height of popularity back then. By contrast, the Harry Potter series is considered popular, but it is overflowing with literary and historical allusions, wonderful characterizations, and a thoroughly character-driven plot. Being popular and literary is not mutually exclusive.
So, for writers who aim to be literary: remember and respect your readers. Unnecessary complexity and obscure writing do not add up to literature. And for writers of popular fiction: read a lot before you ever start writing and always keep reading. That makes for literature and it is not incompatible with popularity. Publishers: be more judicious and bring back a sense of literary mission to put alongside the desire to make money.
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