The document discusses human thinking, writing, and paragraph structure. It notes that human thinking does not follow a logical sequence and jumps around in time and location, but when telling something to someone we impose order and shape. A paragraph maintains unity of thought around a single topic through coherent sequencing of sentences that are connected by structure or idea. The example paragraph establishes its topic in the first sentence and maintains coherence by relating each subsequent sentence back to the author's childhood association with their friend Sylvia.