In a straightforward way, there is nothing particularly exciting about how Exodus Chapter 12, sets up the Mitzvos of Pesach starting with Rosh Chodesh.
It’s simply a starting date. After all, if the Passover Lamb has to be offered on the 14th of the month, then we need to know when that month begins. It’s like someone telling a friend, “It’s noon right now. Meet me at 5pm sharp.”
Yet the Medrash makes a big deal out of it. At the start of his commentary to Bereishis, Rashi calls the Mitzvah of Rosh Chodesh “Mitzvah Rishona she’nitz’tavu bah Yisrael”, the first Mitzvah that the Jews were given. What’s so special about this Mitzvah in particular.
The Masechta that discusses Rosh Chodesh extensively is Masechta Rosh Hashana. Over there, all the emphasis is placed on the fact that it is the Jews, the Jewish Supreme Court, that determines the date of each and every Rosh Chodesh.
Why is this seen as a big deal? After all, in any country, one would expect the ruling authority to decide dates and times for public needs.
The big deal is the word “Lachem”, this month is FOR YOU, the first month. According to the Gemara, this means that the Jews are to determine the functioning of the calendar not only because they are the government. Rather, the image we are given is that God Himself is giving away control of His datebook, his planner, to the Jewish People.
A slave, or any true subordinate, is told when he has to do things and be places.
But a partner asks another partner, “When can we meet? Does Tuesday or Wednesday work for you?”
Calendars have a big undercurrent of hierarchy. Anyone who has ever had to get in touch with anyone important, a doctor, a banker, a CEO, knows that the most important person is the scheduler.
Think of Google Calendar. You can create any kind of Calendar, for you, your kids, your work etc.
One of the features of the program is that you can share the calendar with others. The owner of the calendar can decide how much he wants to show or share. The settings are
Can See only free/busy
Can see all event details
Can make changes to events
Can make changes to events and manage sharing
This moment of “This renewal of the moon is yours!” is putting us on the highest setting. We can manage events and manage sharing!
As the Mishnah in Rosh Hashana says, God told the Jews, “You [decide the calendar]. Whether on time or not on time, these are the only holidays I have.”
Rosh Chodesh Nissan is the first step in God telling the Jewish People that it is not (just) His subordinate, it is His partner.