Paul uses two metaphors to describe the effect of the Torah: that of an heir under a guardian and that of the son of Hagar, Sarah's slave. These examples are often cited as evidence that the Torah is done away with. This is a misunderstanding. Just as the two sets of tablets given to Moses were identical, the conditions of the New Covenant are the same as the Old. The difference is where God's law is written: on tablets of stone or on the human heart. Once the Torah is written on the heart one does its precepts because he wants to, not because he is told to.
