I was seventeen when this priceless piece of advice came my way. I’m now almost fifty, and although I don’t often draw out the rectangle anymore, this charming and simple blueprint is buried deep in my cerebral cortex, lit up like the flux capacitor in “Back to the Future.” I still use it. Still think about it every time I sit down to write one of these things you are reading right now. I continue to admire its impersonal and ruthless forward thrust. And, when I walked into those dreaded A-levels, that little doodle was the first thing I did, directly onto the desk, and with immediate results. My breathing slowed. I felt calm. Bob’s your uncle. What had seemed an impossible task transformed into a practical matter of six little arrows, radiating around a central concept. And arrows one and six were already settled! (I still write the opening and last lines of an essay first.) So now this is really just a four-arrow affair? In my experience, every kind of writing requires some kind of self-soothing Jedi mind trick, and, when it comes to essay composition, this rectangle is mine.