Monkey Cage

Start with a large cage containing five monkeys.

Inside this cage, hang a banana on a string.

Before long, a monkey will reach for a banana.
As soon as he touches a banana, spray all of the other monkeys with cold water.

After a while, another monkey will make an attempt with the same result - and all the other monkeys are sprayed with cold water.

Pretty soon, when any monkey tries to grab a banana, the other monkeys will try to prevent it.

*Put away the cold water.*

Now, remove one monkey from the cage and replace it with a new one. This new monkey will see the banana and start to reach for it. To its surprise and horror, all of the other monkeys will attack it.
After another attempt and subsequent attack, it learns that if it tries, it will be assaulted.

Next, remove another of the original five monkeys and replace it with a new one. The newcomer goes to the banana and is attacked.

Repeat this for each remaining original monkey.. every time the newest monkey takes to the banana, it is attacked.

Most of the monkeys that are beating him have no idea why they were not permitted to have the banana or why they are participating in the beating of the newest monkey.

After replacing all the original monkeys, none of the remaining monkeys have ever been sprayed with cold water. Nevertheless, no monkey ever again approaches the banana.

Why?

Because it has always been that way.