I have been interested in astronomy since I was seven years old, so one of the things I find very interesting about our Hebrew calendar is that almost every event on the calendar corresponds to a particular phase of the moon. Every time a holiday comes around, you know that when the event connected with that holiday happened, the moon was in the same phase as you see on the holiday. For example, the moon is always full when Pesach and Sukkot begin, Rosh Hashanah begins on a new moon and so on.



One of the really interesting things about parashat Devarim (the opening of Deuteronomy), which is always read immediately before Tisha B'Av, is how precisely it is placed in the calendar. The text states that Moshe began his address to the people of Israel in the 40th year after leaving Egypt on the first day of the 11th month, the new moon. The 11th month is known to us today as Shevat. Since we also know that Moshe died on the seventh day of the 12th month, Adar, at about the first quarter moon, Moshe only had 36 days to live when he began his climactic oration to our people.



It is not mere coincidence that we always read Devarim on the Shabbat immediately before one of our holidays most powerfully associated with the calendar, Tisha B'Av. It is our tradition that even in times of greatest joy, we remember tragedy and in times of tragedy, we carry hope for the future.



Devarim stands at one pole of our history and represents the people of Israel standing on the threshold of a dream - taking possession of the Promised Land is about to begin. Israel's future as a nation lies before it.



Tisha B'Av stands at the opposite pole. It represents our national disasters - the destruction of our two Temples by the Babylonians in 586 BCE and by the Romans in 70 CE, and the ensuing centuries of dispersion and oppression.



Shevat and Av stand at opposite ends of the year. Shevat is in the midst of the winter season, the time of rain that brings the promise of new life. Av, six months later, is at the height of the summer heat, when no rains fall and the much of the green life that came in the spring withers and dies.



If you go to Jerusalem today, you can see the poles of Devarim and Tisha B'Av together. At the Kotel, you can see the joy of Jews from Israel and around the world returning to Jerusalem, representing a bright new beginning for our people. Yet, when there, one need only look up to see that our holiest place, Har HaBayit, the Temple Mount, is dominated by edifices built by foreign invading conquerors atop the ruins of our Temple. Those structures serve as a constant reminder that our Temple was destroyed on Tisha B'Av.



In Devarim, as Moshe began his oration under the new moon of Shevat, the 11th month, the time of the winter rains, our nation of Israel stood with a battle-tested army of over 600,000 men that had seen victories over Amalek, Midian and Amorite kings, ready to march into the destiny of the land G-d promised to us, ready to build a life and a nation in that beautiful country.



Then, during the first days of Av, look up as the moon progresses from crescent and passes its first quarter, for Av, the fifth month, is the time of the withering summer heat. Remember that when the moon was in these same phases at the height of summer 1,934 years ago, it was the Roman legions of Titus Flavius Vespacianus that were marching forward. These were the same legions that, two days after the previous full moon, had smashed through the walls of our capital, Jerusalem. On these very days 1,934 years ago, the Roman enemy was already inside the lower city, burning it and killing our people, and when the moon was just past the first quarter, just as it is every year on Tisha B'Av, the Romans burned the Temple to the ground and made sacrifices to their pagan gods in its courts.



At the time of the events in the book of Devarim, Israel stood united. This unity was to the point that even though two and a half tribes already had the holdings they wanted, they had pledged to march at the front of the army to stand with their fellow tribes until they were all secured in the allotted portions. However, on this very week, 1,934 years ago, even as Jerusalem was besieged by the Roman enemy, numerous Jewish factions were fighting against each other within the city, even as it was burning.



The poles of history represented by Devarim and Tisha B'Av represent a moment of testing for us today. This era is one of great promise, with the restoration of a sovereign Jewish State in the Land of Israel, yet we are beset by enemies too numerous to count ? terrorists who blow up children traveling to school, enemies who conspire to turn the world against Israel, enemy powers who plot to build ever more terrible weapons with the avowed purpose of using them against Israel, mobs in the streets of cities around the world who target people with violence because they are Jewish. These threats can unite us and embolden Israel to persevere as we carry on and we build our future together.



At the same time, we as a people are beset by numerous divisions - divisions of observance and movement, divisions of cultural origin, divisions of our views on what is in Israel's best interest, even divisions as to who is to be counted as part of our Jewish nation.



At this moment in time, we, Am Yisrael, the nation of Israel, in our homeland and around the world face the test - will we stand together as our 12 tribes stood as one on the plains of Moav in the book of Devarim, ready to confront our enemies and bravely build a future together? Or, will we be as in the year 70, with the enemy breaking through our defenses? Will our divisions waste our strength and facilitate our own destruction?



This week, of all weeks, we must face this test.