The first gorilla approached the ladder, and when he touched it a strong stream of cold water hit all the gorillas. When he backed away from the ladder, the water stopped. This left the gorillas confused. What had they done wrong?
So, the next gorilla summoned up the courage to approach the ladder. The same result happened.
The next time a gorilla approached the ladder, the whole group attacked him.
One by one, the gorillas were replaced in the cage. As each new gorilla tried to get the bananas, the group attacked him.
Finally, all the original group of gorillas had been replaced. None of the gorillas remaining in the cage had any idea why the group attacked a new gorilla for approaching the ladder. None of them knew exactly why they participated in the attack.
The reason? It had always been that way.