The myth of the novelist as genius: The writer locks himself in his chilly garret, works flat out with little sleep and less food using an outmoded instrument (a quill pen or a forty year old Olivetti typewriter), and emerges with a fully realized work that perfectly explicates the human condition. That novel then becomes a classic to be read by generations of high school students and undergraduates.
What does that version conveniently elide from the process? Advances, printing, book tours, publicity, delivery, royalties, and so on. The fact is that though things were much simpler in the fifteenth century, variations of these intermediate steps were there even when William Caxton was printing the first English books (he was in it to make money after all). We cling to the Romantic idea that if someone writes a worthy story, it makes it into the hands of the reading public with no fuss. But behind every author is a good editor and behind every good editor is a publishing company whose functionaries have decided an idea is marketable. And of course a good writer has very little chance of coming to the attention of a good editor without a good agent. Aha, you might say, but didn't Stephen King write his breakout novel
Carrie in the back room of a laundromat? He had a good agent.