Anyone who has a temper as bad as mine will eventually learn to do two things:

1) Patch drywall
2) Apologize

Drywall is the easier of the two, especially if you went to art school and can wield a damp sponge with reasonable confidence. Apologizing is much tougher. You can do it artfully but, as with drywall, some visible damage will usually remain.

I find both activities provide valuable time for reflecting on the decisions that led me to cause the damage in the first place. The lesson is a simple one: Breaking things may be hard, but fixing them is a pain in the ass.

Still—some things, we should break.

The New Year’s celebration at our dojo—as at many martial arts schools—is called Kagami Biraki, which means, literally, “breaking the mirror,” or sometimes “opening the mirror.” It’s a time to take stock of where you are and re-commit to your training in the coming year.

The metaphor of “breaking the mirror” is ironic given that the mirrors are our dojo’s most treasured, and zealously protected, possession. Almost any fast-moving activity (especially if it involves children) will elicit a chorus of “Watch the mirrors!” from the black belts.

We’re protective of our mirrors because our dojo was mirrorless for many years (it was also windowless, and heatless; it was short on everything but open space and wasps, really). The absence of mirrors was particularly irritating to me because I am addicted to visual feedback. Not just at karate, but everywhere I go. In truth, I react to any mirror as if I were a parakeet: “Hello! Who are you? Do you find me intimidating? No? How about now?”

But leaving my own narcissism aside, visual feedback is a very helpful teaching aid, particularly in a karate class. It shows the learner exactly what she’s doing with her body, which is often strikingly different from what she thinks she’s doing. So everyone at Sun Dragon was thrilled when, a year after we moved the school into a new building, one of our students arranged the donation and installation of a full wall of mirrors.

It was like bringing eyesight to the blind, when those of us who’d been training without mirrors for years were suddenly able to see everything we were doing. I knew, for example, that I had a tendency to slump in some stances, to lean forward instead of rotating into a punch, and to drop my hands—all very bad habits.

I didn’t really need the mirror to tell me these things; my teachers have told me, plenty of times, and I’ve certainly suffered the consequences of dropping my hands often enough. The mirror, however, reminds me in a kinder, gentler, and more consistent way. Instead of having my flaws pointed out to me now and then, I’m confronted with them all the time. It’s sort of like knowing you’re under surveillance; it puts you on your best behavior. I have high hopes that the mirrors’ continual display of my flaws will eventually allow me to correct them. In the meantime, it helps keep me humble.

The mirrors provide wonderful, clear, real-time feedback, and we’re delighted to have them. But what I had forgotten about mirrors, or perhaps never previously realized, is that they also play merry hell with one’s sense of direction.

Around the age of six, most of us learn to tell our right hand from our left. It’s a gross motor skill we acquire early and use constantly, without even thinking about it, and we assume once we know our right from our left, we’re set for life. This is basically true unless you study karate long enough to make the leap from student to instructor. Once you become an instructor, you learn that in fact there are two rights, and two lefts, that you are responsible for: There is right and left for your students, who are facing you, and then there is right and left for you while you are teaching, which is usually (but not always) the opposite of the right and left you learned at age six.

At my school, instructors “mirror” techniques for the students. So, for example, when I lead a class through basics, I face the students and say, “Right hand back!” And all the students pull their right hands back preparing to punch, while I pull back my left hand. This sounds simple but actually, moving one side of your body while stating out loud that you’re moving the other side of your body produces a surprising amount of cognitive white noise.

You can’t just re-learn left and right as the opposite of what you knew, either, because you don’t teach all the time. You need your old right and left for the times when you’re a student, or outside the dojo—say, driving a car. And sometimes when you teach, you face the same direction as your students, so your right is their right, and everyone’s left is the same too.

It’s complicated, but after several years of effort my feeble brain had synthesized left-right orientation and front-back orientation. Then I was able to “flip” left and right in my head to match what my students were doing, when I needed to.

I was very proud of this ability, until we got the mirrors, which introduced a third and fourth version of left and right—what I now think of as Instructor-left-and-right, Reflected; and Student-left-and-right, Reflected. Giving them these names does not help me process them; not at all.

Now, if I look into the mirror while teaching, all the flavors of left and right collide in a hideous tangle, a dimension of infinite rights and lefts. It feels like I have a lot more than just two arms, and I wonder if this is what people recovering from a stroke experience as they try to relearn simple skills.

This right/left, mirror/reality confusion has forced me to consider that perhaps mirrors are not the ever-obliging pals I had always assumed them to be.

I don’t have a lot of mirrors in my house (because if I did, I’d never get anything done), but they still seem to surround me. Looking in a mirror is probably one of the last things most of us do before leaving home in the morning. For the same reason, hotel rooms always have a mirror on or near the door, so before you cross the threshold into public space, you can check and make sure that you either conform to expectations or exceed them, whichever look you’re going for.

There are mirrors in bars and restaurants, all over shopping malls, near elevators, on the sun visors in our cars; you name a surface, someone has tried to make it reflective. And, you may have noticed, places where women congregate are generally shinier than male-only or co-ed spaces. Cosmetics counters, for example, don’t just have mirrors; their every inch glitters.

EVERYONE IS LOOKING AT YOU,” is the not-so-subtle message. “ARE YOU SURE YOU DON’T WANT THE UNDER-EYE CONCEALER WITH WRINKLE REDUCER?”

And while I’ve never had the guts to find out for sure, I’d be very surprised if the men’s changing room at the gym has as many mirrors as the women’s changing room.

At the gym on the campus where I work, a gal can’t get away from them. You can watch your entire trip through the dressing room in the mirrors, like a dreary little TV show starring you: Wrestling with your swimsuit, forgetting your locker combination, getting into and out of the shower, combing your hair, tying your shoes; all the way up until you walk out the door, where you can pause in front of the full-length mirror for one final eyeful. Then you get out onto the gym floor and what do they have in front of the cross-training machines? More mirrors. Even for me, it’s a bit much.

I understand the motivational aspect of having lots of mirrors at the gym, but honestly, don’t we have anything better to do than worrying about who’s the fairest of them all? The proliferation of mirrors gives the impression that our every move is being scrutinized by others, all the time. For all of us not named Lindsay Lohan, that’s simply not the case. And all I can say is, thank God.

The mirror doesn’t lie, but it is a horrible gossip and the truth it whispers can confound us in lots of ways. It twists our awareness of right and left; it lets us pretend to be our own audience; it encourages us to be paranoid and self-conscious. All the information it provides can propel us in directions we don’t want or intend to go.

And worst of all, the mirror leads us to believe that what we are right now is static, and inescapable—that the present outweighs the future. Mirrors lecture us with terrible authority: “This is what you look like. Face up to it!” We adjust our self-image to the mirror’s pitiless testimony as we age, or gain weight, or simply persist in looking the way we wish we didn’t. You can’t deny what the mirror says about you, and the truth can be paralyzing.

What the mirror can’t show you is your potential. So sometimes, you have to break the mirror.

For 364 days out of each year, students at my dojo look into the mirror, and we try to do so without flinching. We accept our faults, we note our strengths, and we learn about who we are. But on the first day of the new year, we put aside who the mirror says we are, and think about who we might become.

When you break the mirror, you destroy its weird trickery of right-is-left, personal-is-public, and now-is-forever. Breaking the mirror shatters the self that you are at this moment, and releases who you could be.

Who? Maybe a black belt, if the eighteen installments of this column haven’t completely destroyed your illusions about what that means. Maybe just someone happier, stronger, more confident or more committed. Maybe you could be a person who doesn’t have to constantly apologize and patch drywall. That’s a good one; I’m working on that.

The point is that anyone can improve upon what they are, but a mirror can’t tell you how. The only way to find out how, is to start. Which can be a pretty terrifying project unto itself. The most difficult technique in all of martial arts, I tell students, is walking through the door of the dojo for the first time.

If you never look away from the mirror, you never get to see what might be. “I am half-sick of shadows,” said the Lady of Shalott, just before Tennyson, that misogynist old bastard, killed her off for daring to look away from the mirror. Cosmetics companies, fitness clubs, Victorian Poets Laureate—they all convey the same warning: You must not look away from the mirror.

Don’t believe them. Look in the mirror, yes. And then break it. Break it and go on, and be what you will.