A Three-part foumula for structure in an essay.
(1) Thesis (the governing idea).
(2) Really? (discussion, quotation, explanation, interpretation, argument, etc. to support the thesis--all this in answer to a hypothetical question about the thesis: "Is it true?").
(3) So what? (some kind of concluding statement about why the now-established thesis is interesting or valuable). You might even ask yourself, "so what's the big deal?"