The Jewish people had traveled for forty years in the Desert. They were standing in Arvos Moav, on the banks of the Yarden (present day Jordan) ready to enter the land of Eretz Yisroel. Moshe, who would not be coming with them, rose to speak to the Jewish people for the last time before his death.

Although he would go on to review virtually the entire Torah with the Jewish people, Moshe chose to begin with some words of rebuke. His style of rebuke is quite instructive. Moshe did not tell the Jewish people anything that they did not already know. Rather than teach the Jewish people new philosophical concepts or explain the enormity of their actions, Moshe chose to simply hint to some of the worst sins committed by the Jews in their travels. He began with a list of place names: The desert, the Aravah, the Yam Suf, Paran, Chatzeiros…

These were the locations where the Jewish people had rebelled ungratefully toward Hashem, threatened to return to Egypt, participated in the rebellion of Korach, and listened to the words of the spies. Moshe hinted to these sins and the sin of the golden calf, but he did not elaborate – he left it to the people to draw their own conclusions.

R’ Aharon Kotler and others explain that that this is the essence of Mussar. Mussar (often translated as rebuke), is not about more information and more guilt; Mussar is about examining our actions.
Before we act we need to think: Why am I doing this? Should I be doing this? Is this action rooted in anger, revenge, arrogance, despair, or in the desire to do the will of Hashem? We need to train ourselves to think before we act and before we speak. And the only chance we have of fixing our mistakes is if we can train ourselves to think after we act. True Mussar is the examination of our own actions.

Moshe’s only goal in rebuking the Jewish people was to get them to rethink and reexamine their actions. That was enough.

The Medrash points out that these words of Moshe are introduced with the words “אלו הדברים” the same words that precede the Ten Commandments. This is to show that self-improvement and Mussar are on the same level as the Ten Commandments.

Shlomo Hamelech writes in Mishlei (4:13): “החזק במוסר אל תרף נצרה כי היא חייך” – “Grab Mussar and do not let go. Guard it – for it is your life”.
The Vilna Gaon writes, “It is our life, because the purpose of our existence is to “break that which we have not yet broken”. We must be on the constant lookout for character flaws that we have not yet conquered. A person must constantly improve himself because if he does not למה לו חיים? – What is the purpose of living?”

Reb Aharon concludes: We say in Maariv every night “כי הם חיינו” – that the Torah and Mitzvos are our life and yet Shlomo Hamelech insists that it – Mussar – is our life. If Torah on its own were good enough, we could have studied it without coming into this world. In fact we do study the entire Torah before entering this world. Our purpose then, in entering this world is to complete our Torah with Mussar – the constant evaluation and re- evaluation of our real life actions.