One week after Tisha B’Av, the saddest day in the Jewish calendar, comes a minor holiday whose mood is precisely the opposite. The festival of Tu B’Av (the fifteenth of Av) is called “the happiest day in the Jewish year” in the Mishnah (Ta’anit, Chapter 4). The practice on this day was for single Israelite women to go out in the vineyards, dressed in white, and dance before the young men. Coupling ensued. Inspired by this, many modern Jewish organizations use Tu B’Av as an excuse to hold singles events.
One other ancient Tu B’Av observance is much more solemn, but no less joyful. The Talmud says that in biblical times the Israelites wandering through the desert would dig their own graves each year on Tisha B’Av, and everyone would be required to sleep inside those graves. Each year, many would die. Then, in the fortieth year in the wilderness, nobody died. Fearing they got the date wrong, the people dug graves and slept in them again. This went on for an entire week, until Tu B’Av, when nobody died and it was accepted as a miracle–and the Israelites’ entrance into the Land of Israel happened soon after (Yerushalmi Ta’anit 4:6).