Almost 20 years ago I really agonized over this question, or one very much like it, as I sought to put a purpose to the work I was doing. I ended up with something like "I want each person to be able to live their lives and express themselves as fully as possible..." But of course there's no end to the list of people and institutions who view education as something we do to someone else that turns out to be for our benefit. And I just can't abide that sort of definition. But that's how we get purposes like "to prepare everyone for vocations" and "keeping the country competitive" and even "unlock opportunity." And that's how we get to definitions of the purpose of education that include things like 'content knowledge' and 'skills' and 'habits of success' and the rest.