The approach to structure in factual writing is like returning from the grocery store with materials you intend to cook for dinner. You set them out on the kitchen counter, and what’s there is what you deal with, and all you deal with. If something is red and globular, you don’t call it a tomato if it’s a bell pepper. To some extent, the structure of a composition dictates itself, and to extent it does not. Where you have a free hand, you can make interesting choices.
from “Structure: Beyond the picnic-table crisis” by John McPhee, published in the The New Yorker‘s “The Writing Life” section in the January 14, 2013 issue