We were two cars on a one-lane road. I was dawdling in thought and, as a result, in speed. In retrospect, I don’t believe the driver behind me meant to impose. If our positions had been reversed — if I had been following a dawdler — I would have driven closely, too. Only luck determined which of us was in front and which behind.

The day had been full of additive frustrations: billing checklists to comply with, forgotten passwords, new charting requirements. Opposition was useless. But this was different: Here was an opportunity to wield cosmic wrath.

I slowed the car to a crawl. It was an act of defiance. En garde: Let us suffer equally for this day I’ve had, even though you know nothing about it!

She started to pull ahead (I would have done the same thing), but as she passed on the left, all my displaced rage surged. Before I could grab hold of my fingers, one of them had made an awful gesture. To be honest, it gestured twice.

The act was aimed at the day, not the driver — but it wasn’t without satisfaction. Cosmic wrath had found an anonymous mark. This little battle between strangers was over.

Then the road opened into two lanes, with a yellow light ahead. We were going to have to wait together through the red. She was waiting already, and though I drove with bricks on the brake, her passenger window was open when I pulled up alongside. She leaned over.

I expected fury. When it comes to road rage, no one picks up the glove gently. They fling it back with force. Instead, her expression was perplexed, polite, and wounded.

“Why did you do that?’’ she said. “Why did you do that? I was only passing you.’’

En garde: shamed into recognizing myself! For those of us who are not yet evolved beings, these are the moments of change. It’s only when a window opens and a face appears — when, in other words, what was anonymous becomes personal — that you see what you have done.

Elissa Ely is a psychiatrist.