Jews don’t have a double identity, but they live with two calendars – the secular, solar or Julian calendar, and the Jewish calendar based on the moon’s cycles.

The Julian calendar, introduced by Julius Caesar in 45 BCE, recognized the need for a universal calendar. Before that date, the national calendar was influenced by Rome’s political leader’s whims, and no one could ever be sure what the date was or would be anywhere in the world. The Julian calendar was designed to resolve this dilemma and align with the year’s seasons. It was adopted first by the Roman Empire and later by the rest of the world.

On the other hand, the Jewish calendar was initiated by Moses as described in the Torah while the Jews were still in Egypt and continued to rule the Jewish year.

“The Lord spoke to Moses and Aaron in the land of Egypt, saying, This month shall be for you the head of the months; for you, it shall be the first of the months of the year.” (Exodus 12:2)

According to the Jewish historical timeline, that date would be 2448 on the Jewish calendar or 1313 BCE. Similar to the Julian calendar, this calendar also aligns with the natural seasons of the year. So it can be relied on for agricultural events, holidays, and commemorations. In this way, everyone knows when the different plantings and harvests occur and how they correspond with various pilgrimage holidays, Passover, Sukkot, Shavuot and all other dates.

The Jewish calendar has four different New Years, each with a purpose. While this may seem strange at first glance, it is not so different when you consider that the modern American calendar may have a traditional New Year (the first of January), an additional new year for taxes, yet another new year for the Government’s fiscal year (in October), and another day that marks the start of the public school year (in September).

The first new year, the month of Nissan noted above, is connected to the holiday of Passover, which marks the redemption of Israel from the slavery of Egypt in the spring of the year.

The second new year is Elul, the sixth lunar month after Passover. It usually falls in late summer and legislates economic issues such as animal and vegetable tithes (taxes). It also calculates the start of the Sabbatical year (7th) when all the land in Israel was to be left fallow, and the Jubilee year (50th) when the land was again required to be left fallow, and also, all monetary debts and mortgaged land was to be rescinded. Since these practices have been defunct since the destruction of the Second Temple in 70 AD, these dates have little current consequences but continue to be noted by Rabbis and halachic authorities.

The third new year is the first day of Tishrei, the seventh month. This is the month most Jews recognize and call their New Year, Rosh Hashanah.

The fourth New Year, Tu B’Shvat, the fifteenth day of Shvat, usually falls between January and February and is the new year for trees. Tu B’Shvat was the starting date for determining the age of trees planted in the land of Israel since, according to the Torah, Jews are forbidden to consume the fruit of a tree growing in Israel that is less than three years old. Unlike the first of Nisan and the first of Elul, Tu B’Shvat is still widely observed worldwide as a minor Jewish holiday, and in the land of Israel, it does mark the beginning of the new sap, the budding of flowering spring trees.

The Kabbalists of Tzfat started the tradition of having a Tu b’Shvat seder, honouring the seven species of vegetables and fruit native to the land of Israel that are mentioned in the Torah. And more recently, the day has become identified with ecology and agricultural sustainability.

An analysis of the Jewish calendar reveals Jewish time’s interconnectedness, with Jewish holidays, Jewish precepts/mitzvahs and practices going back five thousand years.