Calendrical complexities
The portion of HaChodesh, from Exodus chapter 12, is read each year just before the commencement of the month of Nisan.
It designates this as rosh chodashim – “the head of the months”, with the result that Jewish children learn to recite the months of the year beginning with Nisan, when Pesach occurs.
The counting of the years, however, begins with Tishri, the month of Rosh HaShanah.
The result is that we have two systems – months and years, two calculations of the passing of time, and two extra complexities for a Jewish child to master.
The difference between Nisan and Tishri shows the type of history that each month represents. Nisan stands for Jewish national history, inaugurated by the Exodus from Egypt and the emergence of the people of Israel.
Tishri (though some have a different view) is the time of Divine Creation and thus the beginning of the history of the world.
The moral is that a Jew is at one and the same time a member of a specific people and a member of universal humanity.
The double identity is spelled out in the Alenu prayer with which every Jewish service concludes. The first paragraph of Alenu is nationalistic, the second universalistic. The first represents the Jew as Jew, the second the Jew as man.
Which identity is the chief one? They both are.