What I gathered:

– essays do not need to be exclusively about English literature

– essays do not need to take a position and then defend it

– an essay is something you write to try and figure something out

– an essay doesn’t begin with a statement but a question

– you should be writing for yourself in an essay; your expressing ideas and thus help forming new ideas; you’re ultimately thinking out loud

– an essay has to come up with answers; a published essay ought to tell the reader something he or she didn’t already know

– an essay should be a search for truth; thus it should at times meander

– fundamentally, an essay is a train of thought; a cleaned up train of thought, as dialogue is cleaned-up conversation; an essay is not a reference work, does not always have an answer and will meander to express interesting ideas