Jubilee is an ancient Hebrew tradition in which every fifty years society is "reset." Debts were forgiven, slaves were freed, property restored to those it was taken from. It's even in the Lord's Prayer, "Forgive us our debts..." Rome adopted this tradition, as long experience had shown them that the practice of lending money at interest inherently destabilized society. Rome instituted numerous limits and occasional outright bans on the practice of usury out of fear that soaring debt would drive their people to rebellion. When Christianity became Rome's official religion, many Hebrew practices were abandoned, including the Jubilee. Without that occasional push of the reset button, Rome's debts piled up until Rome fell.