When a stock has plummeted and looks like a bargain, wise investors know that it might turn out to be a falling knife. For obvious reasons, you don’t want to try to catch it.

The “falling knife” metaphor relates to lots of things in life, from trying to “fix” a partner in the process of self-destructing to trying to help turn around a company that’s going down the tubes.

Over the holiday weekend I learned about another meaning, the literal one. I was making lunch and cutting up some wet vegetables with wet hands when the chef’s knife slipped out of my hand and began to fall. Quickly realizing I was barefoot, I made a split-second decision and caught the knife, slicing my finger.

Luckily my wife is a trained chef and former veterinary technician who’s not the slightest bit bothered by blood and gore. She bandaged me right up. (Yes, I’m fine.)

When I told her what had happened, she recited what they taught her in culinary school, “Never use a knife when your hands are wet,” she said, “And if it slips, you’ve just got to let it fall.”

“But I was barefoot,” I said, “It would have fallen on my foot.”

“That’s why you always wear shoes when you’re cooking,” she replied.

Well, duh. In the space of about a minute, I did three remarkably dumb things in succession that could easily have resulted in disaster. The thing is, I’ve been an avid cook my whole life. My wife says I have better knife skills than a lot of pros. I use a professional kit to sharpen them. I know about knives. And I should have known better.

So why did I do it? The answer to that is the root cause of why everyone tries to catch falling knives, literally or figuratively. One word. Hubris. It means exaggerated pride or self-confidence. It causes you to do things you should never do.

Hubris destroys lives, companies, even nations. I’ve observed it many times. Most leaders are aware of that, but it still doesn’t stop their egos from writing checks that reality can’t cash.

The irony is, thinking you’re special, smart, experienced, self-aware or even humble enough that you don’t have to worry about hubris is in itself a form of hubris. My actions this past weekend prove that.

Confidence is just one step away from overconfidence. It’s a small step that nevertheless crosses a critical line.