Rabbi Yonasan Sacks
The gemara (Megillah 31b) explains that Ezra Hasofer established the practice of reading the klalos sheb'Toras Kohanim, the curses found in Vayikra (26) before the yom tov of Shavuos, and those of Sefer Devarim (28) prior to Rosh Hashana. Tosafos add, in the name of Rabbeinu Nissim, that the klalos of Sefer Devarim, which begin in Parshas Ki Savo, include part of Parsah Nitzavim as well. Because of this takonas Ezra, we always read Parshas Nitzavim on the Shabbos before Rosh Hashana.
The Gaon of Vilna highlights an essential difference between the tochacha found in Vayikra and the berachos u'kallos of Devarim. The tochacha in Vayikra is formulated in the plural, "im b'chukosai timasu", addressing kol echad v'echad, each individual member of Klal Yisroel. The berachos u'klalos of Sefer Devarim, however, which are statements in the singular, embrace the totality of Keneses Yisroel. This collective quality is emphasized by the pesukim of Parshas Nitzavim which follow the tochacha, "v'lo itchem l'vadchem anochi koreis es habris hazos v'es ha'ala hazos" Devarim (29:13) - "not with you alone do I seal this covenant and this imprecation." Rashi explains that the phrase "v'lo itchem l'vadchem" includes even doros hasidim l'hiyos, future generations. Indeed, the gemara (Sanhedrin 43b and Sotah 36b) explains that the principal of communal responsibility - kol Yisroel areivim zeh bozeh - is rooted in this parsha.
The Rambam (Sefer Hanitzvos Shoresh 3) questions the view of the Halachos Gedolos, who together with Rav Saddia Gaon lists berachos u'klalos as one of the 613 mitzvos. In what sense do these berachos constitute a mitzvah l'doros?
Rav Yeruchum Perlow (Sefer Hamitzvos L'Rav Saddia Gaon, Perek 57) suggests that the Halachos Gedolos was not referring to the ceremony and process of the tochacha which was only a hora'as sha'a, but rather to the principle of arvus which is derived from this parsha.
The reading of the berachos u'klalos before Rosh Hashana remind us of the uniqueness of kedushas Yisroel. May we be worthy of the fervent beracha - shetichle shana v'kililoseha - that the conclusion of the year should mark an end of all tragedy and suffering.