The Jewish Lunar Calendar is Born (chapter 12:1–2)
The first commandment given to the Israelites is in Exodus 12:1–2: “This month shall be for you the beginning of the months. It shall be the first month of the year for you.” Rabbinic tradition reads these verses as a mandate to establish a lunar calendar to orchestrate Jewish life, such as the dates of all festivals.
Since certain holidays are seasonal by biblical mandate, like Passover in the spring and Sukkot in the fall, and the lunar month is only twenty -nine-and-a-half days, and a lunar year is about ten days shorter than a solar year which could result in Passover being celebrated in mid-winter, the lunar calendar needed to be adjusted seven times each nineteen years by adding a month to reconcile it with the solar calendar.
According to rabbinic tradition, the new moon had to be seen by two witnesses who testified before the elders or the court; then these officials would declare the beginning of the month and notify Jewish communities in Israel and the Diaspora. It wasn’t until the middle of the fourth century CE that a fixed lunar calendar was introduced, which did away with the need for witnesses and which told when each lunar month and holiday began.
Why does Scripture mandate a lunar and not a solar calendar? We really don’t know. Practical, homiletical, and historical reasons are imagined. It is possible that in ancient times it was easier to fix months based on the movements of the moon. Alternatively, Israelites may have used it to wean themselves from pagan cultures, where the sun was considered a god.
Perhaps its usage suggested lessons. The light of the moon is a reflection of the light of the sun—the moon producing no light of its own—and Scripture wanted Israelites to know that as a nation they had to reflect God’s “light“—Godly values and ideals. It is also possible that the Bible wanted the Israelites to look at the moon’s seeming imperfection, the sliver of a moon at the beginning of the month, and recognize that the world that God created was left in an imperfect state so that people would help God perfect the world. It may also provide hope for people when it seemed as if they were being engulfed by the darkness of oppression, defilement, and persecution—that they, like the moon, would be renewed.
Another understanding of Exodus 12:1–2 is historical. Israelites should consider this month in which they were redeemed from Egypt as the first Hebrew month to give special distinction to the Exodus because the lesson of the Exodus is pivotal. Jews inserted mention of the Exodus frequently into the prayer book and in many rituals, such as the prayer over wine at the onset of the Shabbat meal. And among other things, the Torah requires Jews to treat strangers with consideration, because they should remember that they were once oppressed strangers in Egypt. This law requiring considerate treatment of strangers is so significant that it is repeated 36 times in Scripture.
 This essay is based on my late partner, Dr. Stanley M. Wagner, and my book “What’s Beyond the Bible Text.”