Essays can consist of a number of elements, including: literary criticism, political manifestos, learned arguments, observations of daily life, recollections, and reflections of the author. 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 are counterexamples. In some countries (e.g., the United States and Canada), essays have become a major part of formal education. Secondary students are taught structured essay formats to improve their writing skills, and admission essays are often used by universities in selecting applicants and, in the humanities and social sciences, as a way of assessing the performance of students during final exams.
The concept of an "essay" has been extended to other mediums beyond writing. A fil
The personal and the autobiographical: The essayists that feel most comfortable in this pole "write fragments of reflective autobiography and look at the world through the keyhole of anecdote and description".
The objective, the factual, and the concrete-particular: The essayists that write from this pole "do not speak directly of themselves, but turn their attention outward to some literary or scientific or political theme. Their art consists on setting forth, passing judgement upon, and drawing general conclusions from the relevant data".
The abstract-universal: In this pole "we find those essayists who do their work in the world of high abstractions", who are never personal and who seldom mention the particular facts of experience.
Huxley adds that "the most richly satisfying essays are those which make the best not of one, not of two, but of all