Can being in the right place at the right time play into a writer's greatness? The beat poets arrived on the scene exactly when the world was ready for their poetry. Had he been born in Shakespeare's day, however, Allen Ginsburg might have been dismissed as a hack. Writers like John Steinbeck or Charles Dickens wrote great literary works that captured the social problems of their respective generations; even if they had been born at a different time in history, their ability to turn the world around them into great literature would have likely enabled them to create masterpieces.
There is something to be said for hard work. F. Scott Fitzgerald was known to be a relentless editor of his own writing. As a result, Fitzgerald was not as prolific as some of his fellow writers, but his published works have an almost flawless feel to them. Nobel Prize winner Toni Morrison honed her skill as a writer while working as an editor. Learning how to write, and more importantly how to edit, may separate the good writers from the great writers.
In something as subjective as differentiating good writers from great writers, perhaps the number one factor is public opinion. When an author receives a prestigious literary prize, such as the National Book Award in the United States, Britain's Mann Booker Prize, or the Nobel Prize in literature, greatness is almost instantly thrust upon the writer.
Differentiating the good from the great can be a subjective and arbitrary decision. One person's good is another person's great. Perhaps time alone will tell; as Shakespeare wrote, "Greatness knows itself" ("King Henry IV," part I, Act IV, Scene 3).