An essay is usually a short piece of writing which is quite often written from an author's personal point of view. Essays can consist of a number of elements, including: literary criticisms, political manifestos, learned arguments, observations of daily life, recollections, and reflections of the author. The definition of an essay is vague, overlapping with those of an article and a short story. Almost all modern essays are written in prose, but works in verse have been dubbed essays (e.g. Alexander Pope's An Essay on Criticism and An Essay on Man.) While brevity usually defines an essay, voluminous works like John Locke's An Essay Concerning Human Understanding and Thomas Malthus's An Essay on the Principle of Population provide counterexamples.