The best part about books is that you can always look back at parts that are either unclear, or parts that you’ve missed or liked, and the Torah is no exception. With that in mind, though, why do we need a whole Sefer (Devarim, the book of Deuteronomy) dedicated to review the first 4 books, when all we’d have to do is look back and examine them? Separately, why would you start a book of review with words of rebuke, as our Parsha does?
As Rabbi Twerski points out, the answer lies in a quote by Shlomo Hamelech (King Solomon), who said: “A conceited fool has no desire for understanding, but only wants to express his own views (18:2).” What’s the point of a past if we don’t learn from it? And what’s the point of learning from our mistakes if we don’t keep what we’ve learned and integrate it into our future? As we get closer to Tisha B’av, when both Beit Hamikdashim (Temples) were destroyed on the same day, the question applies even more.. Didn’t the Jews learn from the destruction of the first Temple merely a few hundred years prior? Do we learn from the destruction of both Temples so many years later? There’s a whole Sefer in front of us pointing its finger at itself and the four volumes before it, begging us to read it, and read it again, until we find the meaning intended for us, and use it to enforce what we WILL do. It’s the thirst of knowledge of our past that will lead to the accomplishments of our future.