An eternity clause is a rule written in a legal document, like a contract or a constitution, that says the rule will always be there and can never be changed. Think of it like a promise that will never end. It's like if you and your best friend made a promise to always be friends, no matter what. Even when you both grow up and go to different schools, you will always be friends. The eternity clause in a legal document is similar to that promise between you and your friend. It means that the rule will stay the same forever, no matter what happens in the future. This can be good because it helps make sure that important rules and rights are protected, but it can also be bad if the rule becomes outdated or unfair and can't be changed.