A widespread conviction exists among fiction writers in English that sooner or later one moves on from the short story to the novel. When John Cheever described himself as the world's oldest living short story writer, we all knew what he meant. But with most writers, the move is more a market decision than an artistic one, because the demands and satisfactions of the two forms are in so many ways utterly different. A short story is far less like a novel than it is like a poem. The primary difference between a short story and a poem is line breaks. Think of Anne Carson's Autobiography of Red, and you think, Odd metrics, is it poetry? Of course. Even if she broke it up only after she finished writing it, it's poetry.
The primary difference between the short story and the novel is not word length. A novel is not a short story that kept going, though every short story writer dreams of writing such a story. Neither is a novel a string of stories with discursive and other connective tissue and padding. One of the first things the writer learns is how amazingly little room there is in a good novel for extraneousness, or noise. The primary difference between the short story and the novel is not length but the larger, more conceptual weight of meaning that the longer narrative must carry on its back from page to page, scene to scene. It's not baggy wordage that causes the diffusiveness of the novel, it's this long-distance haul of meaning. In a good short story the meaning is not so abstractable, so portable, as it must be in a novel, but is rather more tightly and ineffably embodied in the formal details of the text. A scene in a short story--and there may be only one--operates with a centripetal force of concentration. But a scene in a novel spins off a good deal of its energy looking not only backward and forward in the text but also sideways, outside the text, toward the material world, to that set of common assumptions considered ordinary life. That energy is centrifugal, opening out, not constantly seeking to revolve upon its own still centre.
Consider the difference in terms of time. Dr. Johnson said, "No man is ever happy in the present unless he is drunk." The seeking of happiness in the present is a spiritual impulse, and also an artistic one (the other kind of happiness), and nowhere in literature is it so purely expressed as in lyric poetry and the short story. In a good short story the crisis exists in present time, it is a point of perfect, drunken poise between past and future, and every word of the text, every nuance of rhythm, every piece of shading and point of light, has been brought to bear upon it. As Frank O'Connor said, in a short story the crisis is the story. In a novel, by contrast, the crisis is only our destination, it occurs as a point in an unfolding of time; it is the logical result of what has come before it, which is as good as to say, of the moral qualities of the hero's choices to date, and it indicates what the future has in store for one who, by having acted this way, has come to this. So while the short story, like poetry, seeks to focus time, the novel, being more like history, being the most secular of forms, seeks to survey it.
This is why when other than market forces are allowed to prevail, the novel is a form best suited to older writers. The minds of older writers have slowed down and stopped jumping around so uncontrollably, they have grown familiar if not necessarily easy with their own contents, their spiritual hunger has been dulled by time and its accommodations, and they are now interested more in the inexorable laws of moral implication than in perfect artistic moments of drunken poise. Also, of course, having more personal history to survey, they have more to work with. They have the material. Young writers are rarely able to maintain the perspective necessary to write good novels, but they do often write good short stories, and they do often write good strange hybrid longer fictions that poeticize the modes of the novel and novelize poetry. Unfortunately, by the time they're writing good novels, they are often no longer writing with the spiritual force of poets. But every once in a while, to the salvation of literary fiction, there appears a mature writer of short stories--someone like Chekhov, or Munro--whose handling of the form at its best is so undulled, so poised, so capacious, so intelligent, that the short in short story is once again revealed as the silly adjective it is, for suddenly here are simply stories, spiritual histories, narratives amazingly porous yet concentrated and undiffused, grave without weight, ordinary but strange, and the unhappy bifurcation of poetry and history is once again revealed as the pernicious cultural illusion it is.
------"Short Story vs Novel," University of Toronto Quarterly, 68 No. 4 (Fall 1999). Pp. 878-79.