Moses’ second and longest discourse extends from 4:44 through 28:69
Moses reminds the people of the purpose of the Law. He reminds them that it was they who did not want to hear the voice of God at Horeb and asked Moses to become their mediator.
As a mediator then, Moses is completing what he had begun forty years ago. After forty years of wandering, he is well aware that the laws given at Horeb need further clarification, addition, or repetition and this is what he sets out to do here.
The belief that God is the author of the law is unique to Israel. Other ancient Middle East societies had laws such as the Code of Hammurabi which was given to them by the King. Therefore, Catholics ought to listen to the voice of Moses for it is the distant echo of the voice of Christ. By hearing what Moses has to say, we gain deeper insight into the Gospels.