You start with a cage containing four monkeys, and inside the cage you hang a banana on a string, and then you place a set of stairs under the banana.
Before long a monkey will go to the stairs and climb toward the banana. You then spray ALL the monkeys with cold water.
After a while, another monkey makes an attempt. As soon as he touches the stairs, you spray ALL the monkeys with cold water again.
Pretty soon, when another monkey tries to climb the stairs, the other monkeys will try to prevent it.
Now, put away the cold water.
Remove one monkey from the cage and replace it with a new monkey. The new monkey sees the banana and attempts to climb the stairs. To his shock, ALL of the other monkeys beat the crap out of him.
After another attempt and attack, he knows that if he tries to climb the stairs he will be assaulted.
Next, remove another of the original four monkeys, replacing it with a new monkey.
The newcomer goes to the stairs and is attacked. The previous newcomer takes part in the punishment - with enthusiasm — because he is now part of the "team."
Then, replace a third original monkey with a new monkey, followed by the fourth. Every time the newest monkey takes to the stairs, he is attacked.
Now, the monkeys that are beating him up have no idea why they were not permitted to climb the stairs. Neither do they know why they are participating in the beating of the newest monkey.
Having replaced all of the original monkeys, none of the remaining monkeys will have ever been sprayed with cold water. Nevertheless, not one of the monkeys will try to climb the stairway for the banana.
Why, you ask? Because in their minds, that is the way it has always been!
This is how today's Congress and Senate operates, and this is why, from time to time, ALL of the monkeys need to be REPLACED AT THE SAME TIME!
DISCLAIMER: This is meant as no disrespect to monkeys.