Hearts and flowers, dancing and courtship: At first glance such pursuits seem more appropriate to Valentine's Day than to any Jewish festival. Yet Tu B'Av, the 15th day of the Hebrew month of Av, could be called the Jewish "sweethearts day."

This year it begins at sunset on Tuesday, July 30 and continues through Wednesday, July 31.

Tu B'Av might be a useful name to recognize when playing Jewish Trivial Pursuit. But in modern times it has little import. The month of Av is less known for this festival than for Tisha B'Av, which falls on the ninth, and is a major fast day on which Jews mourn the destruction of the Temple.

Yet in the times when the Temple stood, Tu B'Av was a major summer full-moon festival. The Talmud notes, "There never were in Israel greater days of joy than the 15th of Av and the Day of Atonement."

On those days, daughters of Israel went out and danced in the vineyards wearing white garments, looking for mates. Each young woman loaned a dress to a friend, so that each was wearing the dress of another.

The young ladies weren't exactly shy. The Talmud records: "The beautiful among them called out [to the unmarried men]: `Set your eyes on beauty'; maidens who came from noble families called out, `Look for a good family.'

"The homely ones among them called out, `Take your pick in the name of Heaven, but on one condition, that you adorn us with jewels of gold.'"

Although dancing in the fields may seem remarkable to us for a Yom Kippur celebration, such behavior apparently left the ancient rabbis unfazed.

But why was the 15th of Av a celebration? One explanation suggests some sort of repeal or reconciliation.

It was the day on which land-inheriting daughters were given permission to marry men from tribes other than their own. As the last summer day on which wood could be cut and set out to dry before the winter rains, Tu B'Av was a traditional time to leave wood offerings on the Temple altar.

Later, it was known as the day when Roman authorities agreed to permit burial of the masses killed at Betar in the Great Revolt (135 C.E.).

Some contemporary Jewish thinkers contend that the day draws its significance from an earlier pagan nature festival, perhaps paralleling midwinter's Tu B'Shevat, the new year of the trees.

Others emphasize that Tu B'Av is an emotional turning point, setting the mood for the reconciliation and renewal of autumn's Days of Awe.

Only a few customs still cling to Tu B'Av: Prayers of supplication are omitted from the daily service; the day is considered an auspicious one for weddings; Torah study starts to increase as the nights grow longer. And some begin adding New Year's greetings to their correspondence.

On Tu B'Av in ancient times, unmarried men and women went out to meet prospective mates. And since it was the maidens' task to proposition likely mates on Tu B'Av, perhaps now, as then, women should see this as a time for taking initiative.

Jewish communities today might focus on this date when considering the important mitzvah of bringing single adults together.

It's a great day for getting engaged.