We are taught that Tu b’Av - the fifteenth day of the month of Av on our calendar - is one of the two greatest days on the Jewish calendar, sharing the title with Yom Kippur. Tu b'Av is celebrated tonight and tomorrow, August 4-5 of this year.
For last year's Tu b'Av Haveil Havalim, I offered a digest of the gemara's explanations (Taanit 30b-31a) for why Tu b'Av is a Jewish holiday.
Here is that information again, with a couple of added notes interspersed:
1. On Tu b’Av, the die-off of the Desert Generation stopped, so that the remaining Jewish nation knew they would enter Israel, and so that Gd again spoke to Moshe (Devarim 2:16-17).
Note, as well, that Tosafot (Bava Batra 121a) offers an alternative explanation of the "end of the die-off" and its association with Gd speaking to Moshe again:
Tosafot notes that a shivah observance beginning on Tisha b'Av would end on Tu b'Av. Gd would not speak to Moshe during a period of mourning, since we are taught that one cannot experience prophecy when he is depressed (Shabbat 30b) - so Gd would only have spoken to Moshe after the end of the shivah period.
2. On Tu b’Av, the Civil War between Binyamin and the rest of the Jews (see the end of the book of Shoftim) stopped.
3. When Moshe announced that Israel’s land would be divided among patrilineally determined tribes, and that men would inherit land, Machlah, Noah, Chaglah, Milkah and Tirtzah requested the power to inherit their deceased father Tzelafchad’s portions. This was granted to them, but among the consequences was a decree that women who inherited land would need to marry within their tribes, guaranteeing that when their sons inherited their land, it would remain within the tribe. This decree was lifted, broadening marriage options and gladdening shadchanim everywhere, on Tu b’Av.
4. After the Bar Kochba revolt was smashed by the Romans in 135 CE, the victors refused to allow us to bury our dead. Years later - on Tu b’Av - the Romans pioneered the now-routine practice of returning murdered Jews, and permitted us to bury them.
5. When the Northern Kingdom of Yisrael split off from the Southern Kingdom of Yehudah, Yeravam, leader of the north, set up roadblocks to keep Jews from the north away from Yerushalayim and the Beit haMikdash. Those roadblocks were removed, generations later - on Tu b’Av.
6. Tu b’Av, coming midway through the summer heat, is when we finish cutting wood for the korbanot of the Beit haMikdash, and so it is a day of siyyum, celebrating completion of this great mitzvah.
Note that according to some authorities, this is the origin of the practice of celebrating completion of a portion of Torah with a siyyum.
7. Tu b’Av comes at around the time when the nights begin to lengthen and the days begin to shorten (not precisely, of course, since Tu b’Av is a lunar date!). From this point on, then, we have less time to work in the fields, but more time to study Torah at night.
ט"ו שמח! Happy Tu!