The Latin verb discurrere meant "to run about", and from this word we get our word discursive , which often means rambling about over a wide range of topics. A discursive writing style generally isn't encouraged by writing teachers. But some of the great 19th-century writers, such as Charles Lamb and Thomas de Quincey, show that the discursive essay, especially when gracefully written and somewhat personal in tone, can be a pleasure to read. And the man often called the inventor of the essay, the great Michel de Montaigne, might touch on dozens of different topics in the course of a long discursive essay.
Longer essays may also contain an introductory page that defines words and phrases of the essay's topic. Most academic institutions require that all substantial facts, quotations, and other porting material in an essay be referenced in a bibliography or works cited page at the end of the text. This scholarly convention helps others (whether teachers or fellow scholars) to understand the basis of facts and quotations the author uses to support the essay's argument and helps readers evaluate to what extent the argument is supported by evidence, and to evaluate the quality of that evidence. The academic essay tests the student's ability to present their thoughts in an organized way and is designed to test their intellectual capabilities.