This year, the Jewish year has 13 months. Since our months start with the new moon, it means that 12 months make just 354 days instead of the 365 and a quarter days of the solar year. If our calendar were solely lunar, our festivals would begin 11 days earlier in the season every year, so Passover would migrate back through winter into autumn.
But this cannot be. The Torah says, "Observe the month of spring and make Passover for the Lord your God" (Deuteronomy 16:1); Passover has to fall in the spring.
So, from time to time - seven times in a 19-year cycle - our year acquires an extra month. Instead of Shevat, Adar, Nisan, we have Shevat, Adar Rishon (First), Adar Sheni (Second) and Nisan. Thus Nisan falls later in the solar year and Passover (Nisan 15) is at the correct time.
Why does the Torah require such a complicated arrangement? Let's first explore the relationship between seasons and festivals. The seasons are very much of the physical world, occurring irrespective of our choices and efforts. The festivals, on the other hand, are spiritual, endowed with special holiness expressed by the commandments associated with them.
When we ally the festivals with the seasons, we link the physical and spiritual worlds. Passover, reliving the Exodus when our nation was born, falls in spring when everything comes to life. Succot, a time when we take stock of the spiritual gifts acquired over Rosh Hashanah and Yom Kippur, coincides with harvest, when physical gifts are gathered from field, vineyard and orchard.
Passover has to fall in the spring, so from time to time our year acquires an extra month
We can learn this linkage as a goal for our own lives. When we eat, work or simply enjoy ourselves, we should do so in a way that befits a Jew. We keep within the bounds of Jewish law: our food is kosher, our relationships are pure. We refresh ourselves or advance in our careers not simply because we like to, but so that we can serve God and help others with more strength and more resources.
But the leap year offers more wisdom than this. The Kedushas Levi (Rabbi Levi Yitzchak of Berditchev, 1740-1809) relates each of the 12 months of the Jewish year to one of the 12 tribes of Israel. Each month has a particular spiritual energy which is expressed by the story of its corresponding tribe.
What about a leap year? How do 12 tribes fit into 13 months? Intriguingly, the Kedushas Levi says that normally Adar corresponds to Joseph. But in a leap year, Adar Rishon and Adar Sheni (First and Second Adar) correspond to Joseph's sons, Ephraim and Manasseh.
The book of Genesis offers a context for this. Ephraim and Manasseh were born into a family where religious tensions were not unknown. Ishmael sought to kill his younger brother Isaac before devoting himself to becoming a crack shot with a bow and arrow. Esau begrudged his younger brother Jacob the birthright and the spiritual pre-eminence which it connoted. Joseph aroused his older brothers' jealousy when his dreams singled him out as their leader.
An uninformed outsider would see Ephraim and Manasseh as an accident waiting to happen. Ha'amek Davar (Naftali Zvi Yehuda Berlin, 19th century) says that Joseph's older son Manasseh liked to engage in Egyptian court life with his father Joseph, whereas the younger Ephraim became a spiritual disciple of his grandfather Jacob. Manasseh's descendant Gideon won a temporary military victory for the Israelites against Midian, but Ephraim's descendant Joshua succeeded Moses as the pre-eminent prophet of his time, splitting the Jordan River to bring the Jewish people into the Promised Land.
In fact, when Jacob blessed his two grandsons, he made it absolutely clear that the younger Ephraim would be greater. Jacob even placed his right hand on Ephraim's head to make the point with deed as well as with word.
But Manasseh did not so much as murmur an objection. He understood that greater or lesser spiritual attainment does not preclude harmony and co-operation, that there is room enough for a Manasseh and an Ephraim, for a Gideon and a Joshua. Generations of spiritual jealousy ended in Manasseh's remarkable silence.
This is the message of the Kedushas Levi. In a normal year, tensions can build up. Joseph, the character for Adar who rounds off the year's religious achievements, struggled to link with those less spiritual than himself. The year's spiritual highlights can be taken purely introspectively without regard for others who are less sensitive to its messages. And likewise, the 12-month year allows the physical round of the seasons to drift out of kilter with the festivals.
But a leap year spurs us to resolve these tensions. Festivals and nature, the spiritual and physical domains, are reunited by its extra month. The example of Ephraim and Manasseh glows forth as we conclude our spiritual pilgrimage through the year, encouraging us to create their harmony beyond as well as within ourselves, looking on others with a kindly eye, irrespective of whether they outshine us or we outshine them.
The message of Joseph alternates with the message of Ephraim and Manasseh on the threshold of Passover in Nisan. Joseph teaches us spiritual excellence, Ephraim and Manasseh teach us spiritual co-operation. Fortified by these ideas, we can approach Passover ready for a new national beginning.
David Lister is rabbi of Edgware United Synagogue
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