From Poe's "The Philosophy of Composition"
 

    There is a radical error, I think, in the usual mode of constructing a story.  Either history affords a thesis--or one is suggested by an incident of the day--or, at best, the author sets himself to work in the combination of striking events to form merely the basis of his narrative--designing, generally, to fill in with description, dialogue, or autorial comment, whatever crevices of fact, or action, may, from page to page, render themselves apparent.

    I prefer commencing with the consideration of an effect.  Keeping originality always in view--for he is false to himself who ventures to dispense with so obvious and so easily attainable a source of interest--I say to myself, in the first place, "Of the innumberable effects, or impressions, of which the heart, the intellect, or (more generally) the soul is suceptible, what one shall I, on the present occasion select?"  Having chose a novel, first, and secondly a vivid effect, I consider whether it can be be wrought by incident or tone--whether by ordinary incidents and peculiar tone, or the converse, or by perculiarty both of incident and tone--afterward looking about me (or rather within) for such combinations of event, or tone, as shall best aid me in the construction of the effect.