Parashat Bo finds us in the more severe end of the plagues that God meted out to the Egyptians. As the Torah is gearing up for the last of the Ten Plagues, there is a sudden break in the narrative.
 
As if an afterthought, we are commanded to set the months of the year according to the cycle of the moon and then we are once more back into the plagues.

Why this interruption of the story?  It is interesting to note that this commandment is the very first we receive as a nation. Before the laws of keeping kosher or Shabbat or even the Ten Commandments, we are told to set up a calendar. In the birth of our nation, is this really where we want to start? With timekeeping?

In the world today, most keep their calendar according the revolution of the sun – a year, in Hebrew shanah. Muslims, on the other hand, go according to the cycle of the moon alone. Thus, Ramadan “travels” from year to year to a different season, 11 days earlier each year.

Jews are the only people that keep to the cycle of the moon and sun together, setting our festivals according to the moon, but adding a month during leap years to ensure that our calendars are seasonally adjusted. 

The Hebrew word for month is chodesh, the source of which derives from chadash, meaning “new”; as opposed to shanah, meaning “year”, from the idea of yashan, meaning “old”. 

The role of the moon is to reflect the light of the sun upon the earth to illuminate it during the dark. 

So to the message to our burgeoning nation, two weeks before the tenth plague and the Exodus: our role in society is a new one, as a nation it will be our responsibility to reflect the light of God on to the world.