Biblical festivals are generally related to the seasonal events on the ancient agricultural calendar in the land of Israel: Pesach with the beginning of the barley harvest, Shavu´ot with the beginning of the wheat harvest and the appearance of the first fruits on the trees, and Sukkot as the time of prayer before the first rains begin for the rainfall needed for sufficient food production.
From another perspective, each of these festivals is connected with a superlative event from ancient Hebrew history, when its identity as a people was forged. Pesach is the time to remember the act of liberation from the yoke of slavery in the land of Egypt. Shavu´ot recalls the giving of the Torah by God at Sinai. Sukkot commemorates the wandering in the desert under God´s protection.
Rosh Hashanah and Yom Kippur, unlike these other holydays, are not related to agricultural times. Yom Kippur, in accordance to the rabbinic tradition, is the day Moses came down from Mount Sinai for the second time with a second set of tablets and with God´s pardon for the sin of having built the golden calf (Moreh Nevuchin 3; 39). Thus the day was established as the day of atonement, as we read in Leviticus (16:30).
Rosh Hashanah is defined in the Torah just as a Yom Teru´ah (Numbers 29: 1) or Zikhron Teru´ah (Leviticus 23: 24), the day on which a ram's horn –shofar- is blown to emit special sounds. In Psalm 84:1 we read a verse that is difficult to understand that relates the blowing of the shofar with of God´s Judgement of human beings (Talmud Bavli, Rosh Hashanah 8, a; b). But it is only in the Mishnah in the tractate of Rosh Hashanah (1, 2) where the meaning of the holyday is explicitly explained:
“At four times during the year the world is judged [by God], on Pesach regarding the quality of the harvest, on ´Atzeret (Shavuot) regarding the fruit of the trees, and on Rosh Hashanah when all creatures pass before God like little sheep [Note: “benei maron” could also be understood as: like soldiers being reviewed in front of their commander (Talmud Bavli, Rosh Hashanah 18, a)], as it says in the verse: “He forms the hearts of everyone, pays attention to everything they do” (Psalms 33: 15). And during the celebration of Sukkot, God judges the amount of rain that will fall."
The sages of the Talmud were the explainers of the meaning of the feast. It is about divine Judgment. The sound of the shofar prescribed by the Torah is meant to awaken the hearts of the people being judged since its sound resembles crying and sobbing (Talmud Bavli, Rosh Hashanah 33, b).
Rosh Hashanah, together with Yom Kippur -- the Day of Atonement on which God pronounces sentence upon each human being, are the terrible days, the Days of Awe, because on them the conscience of each person must be disturbed. They remain in the Jewish tradition as sublime days on which synagogues are overcrowded as during no other celebrations. They are the days on which the Jewish people affirmed and continues to affirm, despite all the iniquities that mar human existence, that “there is a Judge and there is Justice” (Talmud Yerushalmi, Sanhedrin, cap. 10, page 28, column 4, halakhah 2; Bereshit Rabah (Vilna), Parashat Bereshit, Parasha 26)
Happy 5779!