There are some enterprises in which a careful disorderliness is the true method. — Herman Melville, Moby-Dick
An essay (à la Essais de Montaigne, which define the form) is a hike through the valleys and mountains of the mind of its author, attempting, not to definitively answer its principal question, but to exhibit style of thought. Hence, an essay must treat its reader as a walking mate. David Foster Wallace says when we read essays we "watch somebody reasonably bright but also reasonably average pay far closer attention and think at far more length about all sorts of different stuff than most of us have a chance to in our daily lives."
In "On The Essay," David Solway posits that writing always involves the self. Crucially, the writer tries to articulate their fundamentally incoherent primordial self into an analogical self, a literary persona more legible than the primordial self. The essay, with its "deceptively cool, skeptical, investigative, and dispassionate manner" supplies to the reader an object of discussion, a cipher which if unlocked tells us more about the writer than anything else.
The essay's antithesis is the epic poem. Where the essay is a primarily literary form, epics like the Homeric poems and Beowulf are oral performances, and those like the Aeneid and Paradise Lost use a grander style of elaborate, flowing sentences whose effect lies primarily in the impression of the words. And epic poetry frequently relies on formal devices such as epic simile or standardized rhythm, rhyme, or alliteration. When we read an epic poem, we are imbibing a whole culture in one work, not simply discussing something that happened to catch our attention.
It is surprising then that the essay and epic can come together in the same work, the prose poem of Biblical proportions, Shakespearean style, and reflexive discourse that is Melville's Moby-Dick.