[This post is part of the "Working Week" series.]
Ultimately, a composition consists of a series of paragraphs. If you looked only at the topic sentences (usually the first sentences) of these paragraphs, you should get a good sense of how the text is organized and what it wants to accomplish. When writing a text it can therefore be useful to generate an outline simply by listing these topic sentences and perhaps to organize them further using what will turn out to be section headings. You will here need to decide what the organizing principle of the text as a whole will be: a narrative plot, a logical argument, a call to arms, a set of impressions, etc. "It is," says Grierson, "an additional satisfaction if in an essay or a book you can feel at the end not only that you have derived pleasure from this or that part of the work, or this or that special feature—the language, the character drawing, the thoughts, the descriptions—but that as you lay it down you have the impression of a single directing purpose throughout" (1944: 135). The reader should feel, as Aristotle also said, that there was a reason to begin exactly where you began and end exactly where you ended. The composition of the whole text depends on the way the paragraphs are strung together to achieve this single purpose.