Madmen and wheels

It was a day of pouring rain, and Marcos gets a flat tire right in front of an insane asylum. He pulls over, gets out, shelters from the rain as best he can and starts removing the lug nuts that hold the wheel. He leaves them carefully on the ground in a little pile. He takes the wheel to the trunk of the car to swap it for the spare, and when he comes back he accidentally kicks the lug nuts, with such bad luck that they roll away and drop down the storm drain.

“What rotten luck!”, Marcos exclaims, “now what am I going to do?”

At that moment, one of the madmen who was watching the scene from the window calls out to him: “Hey, buddy! Easy! Take one lug nut off each of the other wheels, put those three on this wheel, and drive like that to the next gas station, where you can buy lug nuts and fix the wheel.”

Marcos is astonished, and after hearing the madman’s ingenious proposal he can’t help but thank him enthusiastically: “What a great idea, you nut! How did you come up with it?”

The madman’s answer was immediate: “Because I’m locked up in here for being crazy, not for being stupid!”

I heard this story a long time ago from my boss, and it is remarkable because it explains an important management principle. The question, dear readers, is: which management principle is on display in this joke?