I found this introduction to Devarim in Richard Elliott Freedman’s Torah Commentary:
“The last verse in Numbers is, “these are the commandments and thejudgments that YHWH commanded by Moses’ hand to the children of Israel.” The first verse in Deuteronomy is, “These are the words that Moses spoke to all of Israel.” The difference between commandments and judgments in Numbers and words in Deuteronomy marks an essential change. Commandments and judgments are laws. Now, in the last book of the Torah, Moses does more than give law. Deuteronomy is a book of Words. That is its name in Hebrew: debarim, and that is what it is about. Its first thirty chapters are Moses’ farewell address to his people before his death. It would have taken close to three hours to say it all to them. It contains history, law, and great wisdom. In places, especially near its end, it is beautiful—inspired and inspirational. Moses is eloquent. And that is ironic and instructive when we turn back to Moses’ first meeting with God, at the burning bush. There he tries to escape from the assignment to go speak to the Pharaoh by saying, “I’m not a man of words” (Exod 4:10)! Now he has become a man of words. It is interesting, remarkable, ironic, and inspiring to see Moses’ development through all that has happened in forty years into a man of words. More than any other human in the Bible, Moses grows and changes in the course of his life. One can change: change professions, change values, change lifestyle, change character. One can grow and become stronger and better.
“This is also a change in the presentation of law in the Torah. Most of the commandments in the Torah have been given without reasons or explanations. From the law of the “red cow” (Numbers 19) to the Ten Commandments, one is not told why one must perform them, but only that God commands it (with a few notable exceptions). But the law code of Deuteronomy (12-28) is preceded by eleven chapters of history, explanation, and inspiration, and it is followed by two chapters of exquisite revelation of the relevance and value of the commandments. The Torah thus concludes with the message that the law is meant to be relevant, comprehensible, and meaningful in the people’s lives. It is appropriate to seek out the meanings of the laws and, when interpreting the law, to understand that it is explicitly meant to enhance lives. One must not apply it in a way that causes injury or undermines its positive function in life.”