The trouble with Charlie is that he doesn't know when to stop. If you give him an inch, he takes a mile; if you glance at him affectionately, he nudges your hand, drools on your trousers and gets intimate with your leg. That's because he's a dog and dogs aren't good with boundaries. It's only his fear of reprisal that stops him from pissing on the carpets, raiding the fridge or humping the dog next door. To live with a dog, you have to have firm rules. Dogs like to be in a binary world where good behaviour is rewarded and bad behaviour punished. Hence I tell Charlie that he's a "good dog" or a "naughty boy" and nothing in between.
This is at odds with current "mindset" theory, which dictates that we should focus on the action rather than the subject. But since Charlie, like many teachers, is too busy licking arses to read Carol Dweck, I don't suppose he minds.
I explain this Manichaean canine philosophy to visitors but it's not always noted. Last week, one of my cousins arrived and, despite being apprised of the Domestic Dog and Visiting Family Members Act, subsection 37, clause (iv), which states that "the feeding of titbits is expressly forbidden", she gave Charlie a cheese sandwich. Not only that, she fed him from her fingers. She couldn't have damned him more if she'd given him crystal meth and set him up with a dealer.
The next day, he gave in to his previously subjugated primal urges. During afternoon walkies, he craned his neck across the pavement and gobbled a little girl's ice cream. Remember this the next time you're tempted to flout canine commandments: today's cold sausage roll could be tomorrow's toddler's face.
Students are like dogs when it comes to boundaries. As long as you keep them on a tight leash they behave in a civilised manner, but as soon as you relax control they revert to feral ways. If you want to see how thin the veneer of civilisation is, drop into an English lesson during the last week of term. Under the pretext of "drama", boys will be rampaging around while filming each other on their phones. I think this is the way the world will end: with Tory ministers running around like Rambo, hurling their Dunhill cufflinks as missiles.
I guess this lack of self-restraint stems from us adults. We may be Houyhnhnms on the surface but we're Yahoos underneath. Our students drop their inhibitions for end-of-term fun but we dump our better judgement for profit. Take last month's Vice magazine, which featured models posing as famous writers on the brink of committing suicide. Fashion has done some ugly things in its time but trying to flog frocks on the back of a well-dressed Plath kneeling by an oven plumbs new depths of callousness.
Thankfully, the rest of the world's media duly rubbed Vice's nose in it. But it does prove - like Charlie and the ice cream or the boys in Lord of the Flies - that we're much closer to barbarity than we think.
Anne Thrope (Ms) is a teacher in the North of England. @AnnethropeMs.