Though the holiday of the 15th of Av is not mentioned in the Bible, the Mishnah in the end of the tractate of Taanit tells us: "Israel had no greater holidays than the 15th of Av and Yom Kippur. On these days the daughters of Jerusalem would go out to the vineyards and dance."

The Talmud asks, "It is clear why Yom Kippur is a great holiday—for on this day forgiveness was granted [for the sin of the Golden Calf] and the Second Tablets were given. But what is the 15th of Av all about?" The Talmud answers that numerous joyous events occurred on this day (see Why Do We Celebrate the 15th of Av? for an enumeration of these events).

Can any of the events hold a candle to the Exodus from Egypt?Upon examining these events that occurred on the 15th of Av, it seems that the question is hardly answered. None of these events – and even the combination of them all – seems to justify the establishment of a holiday, and one that outshines all others (even Yom Kippur is mentioned second) no less! Can any of the 15th of Av's events hold a candle to the Exodus from Egypt or the salvation from genocide commemorated on Purim?

Perhaps the key to understanding the unparalleled joyous nature of this holiday lies in the peculiar manner in which it is celebrated: girls of marriageable age would assemble in the vineyards and dance in front of an audience of prospective suitors, in the hope of finding a soulmate. Perhaps the Mishnah itself alludes to this idea:

Question: What is so remarkable about the 15th of Av (and Yom Kippur)? Answer: That the maidens would go out and find for themselves marriage partners.

The mystics teach that marriage isn't really a union between man and woman, it is a reunion. A soul is divided into two halves; one half descends into this world in a male body, the other in a female's body. Marriage is the joyous reunion of these two estranged halves. Every husband and wife is predestined for each other not (only) because they complement each other perfectly, but because they actually share a soul.

This is why of all loving relationships, the love between husband and wife is the most electric and passionate. This passion is a result of years of separation, years of a soul's yearning to achieve wholeness through reuniting with its long-lost other half. When the two finally find each other and reconnect, the resulting emotions are dizzyingly intense.

When the two halves finally reconnect, the resulting emotions are dizzyingly intenseOn a cosmic level, man and woman are metaphors for G‑d and His nation. The soul of the Jew is a "veritable part of G‑d"; we are essentially one with our Creator, just as a husband and wife are derived from one essence.

And we too undergo this process of estrangement and reunion; a process intended to heighten the love and passion, to bring it to levels unimaginable had we never experienced separation. The first time our nation was estranged from G‑d was shortly after our betrothal at Mount Sinai. A few short weeks later we drifted away and worshiped a Golden Calf. The reconciliation and redoubled commitment and love occurred on Yom Kippur—the second greatest holiday on our calendar.

That, however, was a relatively short estrangement. On Tisha b'Av, with the destruction of the Holy Temple and the commencement of two millenniums of exile, we embarked upon a most horrifically painful long stretch of estrangement. The goal? To reach the pinnacle of passion and head-over-heals infatuation. The result of this estrangement will be the grandest wedding of al times, the coming of Moshiach which will usher in an era of eternal marital bliss.

It is this ultimate marriage that we celebrate on the 15th of Av. This day, a mere six days after Tisha b'Av, symbolizes our rebound; the reconciliation that follows the estrangement of Tisha b'Av—and its raison d'être.

That's why the Talmud points to various events that occurred on the 15th if Av, all of which share the same theme—reunion that follows a period of estrangement:

a) G‑d speaks to Moses in a loving way after nearly forty years of a more distant kind of communication.

b) The daughters of Zelophehad are permitted to marry whomever they so wish.

c) The tribe of Benjamin is reunited with its brethren, ending a painful schism.

d) The sentries preserving the divide between the Northern and Southern Kingdoms of Israel were removed.

More than the sum of the parts is the message that these events teache) A precursor of the ultimate reunion: After the massacre at Betar, when it seemed that our estrangement from G‑d was finalized, G‑d revealed that the relationship is still alive and well.

More than the sum of the parts is the message that these events teach: the 15th of Av is the day when we celebrate our rebound.

This is why the maidens dance on the 15th of Av and Yom Kippur. There are no more appropriate marriage-themed days on our calendar. And of the two, the 15th of Av is the more joyous one—for it symbolizes the ultimate marriage.

Of all Jewish celebrations, none equal the joy of a wedding. Of all Jewish holidays, none equal the joy of the 15th of Av.