Rosh Hashanah in Early Judaism

In biblical literature, the first day of the seventh month is designated a holy day only in the priestly calendars of Leviticus 23 and Numbers 28–29. There, it is observed by noisemaking (teru‘ah), interpreted as blowing horns—either trumpets (ḥatsotsrot) or animal horns (shofarot)—the purpose presumably being to call God’s attention to the people’s need for sustenance (a good harvest and adequate rainfall) at this crucial turning point of the year. Second Temple–era literature still understands the day this way. Philo also offers a figurative philosophical and ethical explanation. Only in rabbinic literature is this day considered the beginning of the new year, Rosh Hashanah. Reflected here are two different calendars: one beginning in the spring (the month of Nisan), and the other beginning in the fall (the month of Tishri). (This is acknowledged in the Mishnah, where the festival calendar is still held to begin in the spring.) The former calendar is preexilic, and the latter derives from the period of the Babylonian exile and reflects the Babylonian calendar. For the rabbis, the autumn new year is also a season of judgment, when the world is judged with respect to rainfall and people are held accountable for their deeds of the past year.