Teach the children so it will not be necessary to teach the adults. (Abraham Lincoln)
Lincoln didn’t mean that adults should not be taught; there’s always something of value that mature people can and should learn. Perhaps he was thinking of basic fundamental truths including moral and ethical values that will not have to be re-taught to adults if they have learned them as children.
Start children off on the way they should go, and even when they are old they will not turn from it (Proverbs 22:6).