When the well is dry, people know the worth of water. [so appreciate what you have while you have it]
Benjamin FranklinI think also, that general virtue is more probably to be expected and obtained from the education of youth, than from exhortations of adult persons; bad habits and vices of the mind being, like diseases of the body, more easily prevented than cured. I think moreover, that talents for the education of youth are the gift of God; and that he on whom they are bestowed, whenever a way is opened for use of them, is as strongly called as if he heard a voice from heaven.
Benjamin Franklin