Five monkeys are thrown in a cage by a sadistic monkey-hater. Enough food and water is at the bottom of the cage to keep them alive, but a stalk of bananas waits at the top, alluringly out of reach. A ladder leads up to it.

After getting over the shock of being caged, one of the monkeys scales the ladder and reaches for a banana. All of a sudden a fire hose appears from nowhere. The monkey at the top of the ladder is soaked with cold water. Not only him—all the monkeys are soaked.

Over the next few days, the experiment repeats. One monkey makes a run for the bananas, the whole troop gets soaked, and pretty soon the group starts beating up any monkey brave enough to scale the ladder. The bananas are still at the top. The monkeys reluctantly accept a life without bananas.

Then the experiment changes. The sadist takes one monkey out and replaces him with a new one. The new monkey, not knowing the consequence, immediately starts up the ladder. The other four grab him and beat him senseless. He has no idea why, but he learns: don’t go up the ladder.

One by one, every monkey is replaced. After five days, no monkey from the original troop remains. None of the new monkeys has ever been soaked.

But every monkey knows: don’t climb the ladder.

We’re not sure why. We just know we can’t.