In a well-known passage in De catechizandis rudibus, Augustine explains the purpose of the whole Scripture and of redemptive history:
“Thus, before all else, Christ came so that people might learn how much God loves them, and might learn this, so that they would catch fire with love for him who first loved them, and so that they would also love their neighbor as he commanded and showed by his example – he who made himself their neighbor by loving them when they were not close to him but were wandering far from him. And all of the divine scripture that was written before the Lord’s coming was written to announce that coming; and everything that has since been committed to writing and invested with divine authority tells of Christ, and calls to love. If this is so, then it is plain that on the two commandments of love for God and neighbor hinge not only the whole law and the prophets – the only holy scripture that existed when the Lord spoke these words – but also all the other books of divine writings which were later set apart for our salvation and handed down to us. Hence, in the Old Testament is concealed the New, and in the New Testament is revealed the Old.”
The old covenant is the Lord’s long courtship, designed to seduce us to love the God who loves us.