The Parsha of Nitzavim we read this Shabbat opens: "You are standing today, all of you, before Hashem, your G-d, your heads, your tribes, your elders, and your officers, all the men of Israel; your small children, your women, and your proselyte who is in the midst of your camp, from the hewer of your wood, to the drawer of your water for you to pass into the Covenant of Hashem, your G-d."
The Panim Yafos points out astutely that the reason each category of Jew is stated in Parshat Nitzavim is that Moshe knew above all else the most important goal and directive for the Jewish people should be Achdut (Unity). Where there is Unity there is strength. The Jewish People needs to constantly strive to attain Unity.
It was fitting on the last day of Moshe's life that the overriding principle he wanted to broadcast loud and clear was that Unity trumps all else. It was by design. This is the Parsha we learn out the principle that each Jew is responsible for the other. This is part and parcel of the Covenant that the Jewish People entered into with G-d on the last day of Moshe's life. Rav Zadok explains that the Jewish People entered into three Covenants with G-d. The Covenant that entered into effect on Moshe's last day of life was the third and final Covenant.
As in the second Covenant which was at Sinai those who were not yet born were included although specifically mentioned in the Nitzavim Covenant ("But with him that here stands with us this day before Hashem your G-d and also with him that is not here with us this day"). The first Covenant was made between Abraham and G-d in the so called Covenant Between the Parts (Genesis 15:7-21) which promised the Land of Israel eternally to the Jewish People after 400 years of Bondage. Rav Zadok elaborates further that the Nitzavim Covenant was similar to the Sinaitic Covenant which was made with the "Ten Commandments."
The Nitzavim Covenant starts with the Ten categories of Jews to correspond to the the "Ten Commandments." This is not a coincidence. The Ten categories of Jews will be responsible for carrying out the Ten Commandments which has the entire Torah incorporated into it. The message is to work towards a United Front.
When Unity is achieved, the Jewish People fulfill G-d's design for the world.
Albert Einstein worked his whole life to find a united way to scientifically put the Universe together. He tried to unify the forces of nature together in the Unified Field Theory. Einstein in his own way was a deeply religious man. Where there is unity there is the ultimate strength. May this coming New Year lead to a United Jewish People that can handle the "slings and arrows of outrageous fortune." Shana Tova to all. Shabbat Shalom