Just when you think things can't get any worse - they get better! Welcome to the seven day once-and-future festival which begins with the 9th of Av and concludes on the most beloved of days - Tu b'Av - the 15th of Av. The dramatic change begins even on the day of the 9th itself, for the day of the destruction of the Holy Temple in 586 BCE, and again in 70 CE, is also, according to tradition, the day that the soul of messiah enters the world.
But, as we know, the 9th of Av is a day that from the beginning of creation was ripe with the potential for calamity. In fact, its first manifestation in our history was the sin of the spies who had been sent by Moses to gather spiritual intelligence from the land of Israel, and instead delivered their evil report on this day.
Their punishment, and the punishment meted upon the entire nation of Israel for accepting this report was, as we know, thirty-nine more years wandering in the desert, until the last of the generation had died out. Only then would their children eventually enter the land with Yehoshua.
Midrash tells us that the condemned generation did not gradually drop off throughout the days of the years, but that each year, on the 9th of Av, all the adult males would dig their own graves, and then lay down in them. The following morning only those whose survived the night would step out of their graves. So it was for thirty-eight years. But on the thirty-ninth and final year in the desert, all who had laid down in their graves on the 9th, rose and stepped out of them on the 10th. The decree was over. But rather than feel relief or exoneration, the people felt uncertainty. Maybe their timing was off? Maybe they miscalculated the date? So the men continued to lay down into their self-dug graves each night for the next seven nights until by the night of Tu b'Av, the 15th, they could see by the full moon that they couldn't be wrong: the decree of death was over!
In other words, the grievous sin of the spies was ultimately manifested in a nation-wide fear that the entire children of Israel were somehow out of sync. The very first commandment that the Israelites had received while still in Egypt was to observe the new moon and fix the calendar, yet within the course of one generation they had seemingly lost track of the days. Great was their fear. It was on Tu b'Av, the day of the full moon, that G-d reassured them that all was well. It was on Tu b'Av that they synchronized their spiritual watches and were once again at one with G-d.
The Talmud Tractate Ta'anit asks why Tu b'Av is considered the happiest day of the year, and receives several different answers from several different sages. The answers initially seem unrelated to one another, but now we can understand all the various facets of Tu b'Av in this new light: Concerning the generation of the desert, death stopped the moment they were realigned with G-d. Concerning the lifting of the ban against inter-tribal marriage after the Israelites had settled the land according to their tribal inheritances, having accomplished this, having remained faithfully in step with God's historical plan, they could now mix freely and with unity. And of course the lifting of the ban against intermarriage with the tribe of Binyamin, after the breakout of internecine violence had faded into history, marked a new resynchronization and harmony of spirit for the children of Israel. And yes, even the lifting of the Roman ban against the burying of the dead at Beitar, Bar Cochba's last stronghold, marked a reconciliation between G-d and His people.
Needless to say, the beloved custom of Tu b'Av which took place during the time of the Holy Temple, in which the unmarried girls of Jerusalem, dressed in borrowed white robes, danced in a circle while the young men looked for their future brides, bespeaks of unity, purity and perfection. As for today's popular custom of marrying on the 15th, there is no moment in life that so exemplifies the perfection of timing, or of being in perfect sync with God's world, as the bride and groom marrying under the wedding chuppah.
The three weeks of mourning, know as the "between the straits," (bein hameitzarim), the three weeks of feeling out of step with the universe, not at all in harmony with God's desire to dwell among us, have concluded. Now as we turn our thoughts to the approaching New Year, and to the spiritual stock taking and introspection that our upcoming rendezvous with G-d requires, He has blessed us with the most precious of gifts: We, God's children, are back in perfect sync with Him.
Mystical tradition tells us that it was on Tu b'Av, forty days before the work of creation was commenced, that G-d, in His infinite love and wisdom, determined the betrothal of Israel to the eternal Torah. The 15th of Av: Being in the right place at the right time!
Source. The Temple Institute: