Writing an extended text at an advanced level involves not just the language system. It poses significant challenges to our cognitive systems for memory and thinking as well. Indeed, writers can put to use virtually everything they have learned and stored away in long-term memory. But they can only do so if their knowledge is accessible, either by rapidly retrieving it from long-term memory or by actively maintaining it in short-term working memory. Thinking is so closely linked to writing, at least in mature adults, that the two are practically twins. Individuals who write well are seen as substantive.
