They find pearls on their coasts, and diamonds and carbuncles on their rocks; they do not look after them, but, if they find them by chance, they polish them, and with them they adorn their children, who are delighted with them, and glory in them during their childhood; but when they grow to years, and see that none but children use such baubles, they of their own accord, without being bid by their parents, lay them aside, and would be as much ashamed to use them afterwards as children among us, when they come to years, are of their puppets and other toys. –Utopia,
What is the central idea of the passage?