Rosh Hashanah (Hebrew, “beginning of the year”), Jewish New Year, celebrated on the first and second days of the Jewish month of Tishri (falling in September or October) by Orthodox and Conservative Jews and on the first day alone by Reform Jews. It begins the observance of the Ten Penitential Days, a period ending with Yom Kippur that is the most solemn of the Jewish calendar. Rosh Hashanah and Yom Kippur are known as the High Holy Days.
In the Bible, Rosh Hashanah is mentioned only as a day of remembrance and of the sounding of the ram's horn. These two characteristics of the day, interwoven with the theme of the proclamation of God's kingship, became the major components of the New Year's observance in later Judaism. They are emphasized in the liturgy by the repetition of “verses of remembrance,””verses that mention the ram's horn,” and “sovereignty verses.” The first of these is important because it represents the sense of continuing creation and development of the world that Judaism emphasizes on this anniversary of creation. Because good and evil actions greatly influence the future, it is emphasized that God “remembers,” and mention is made of the meritorious acts of the Hebrew patriarchs Abraham, Isaac, and Jacob to urge emulation of their holiness as the path to redemption.
Indeed, the most prominent scriptural passage in the Rosh Hashanah liturgy is that of the binding of Isaac (see Genesis 22), which forms the portion from the Torah designated for reading on that day. This passage leads into the theme of the ram's horn; in the service in the synagogue the shofar, a wind instrument made of ram's horn to represent the horn of the animal sacrificed in Isaac's stead, is blown. Early peoples often made noise at the New Year to drive away demons; the Jews transformed this practice into a blowing of the horn to prefigure the moment when God would destroy the evil in the world, “blow the ram's horn, and come with the whirlwinds.” At that moment, it is held in the “sovereignty verses,” God will be king over all the earth, as he is now king over those who accept him in a renewal of commitment on Rosh Hashanah.