The Jewish people set aside one particular day to commemorate the many calamities that have befallen them throughout history. Tisha B'Av is literally the ninth day of the month of Av on the Hebrew calendar. Normally it falls in August.
According to tradition, it is the date of the destruction of the First Temple in Jerusalem and the beginning of the Babylonian exile. It is also the date of the destruction of the Second Temple by the Romans and the beginning of the Diaspora. And it is the date of the decree expelling the Jews from Spain in 1492.
It is a day Orthodox Jews mark by fasting and mourning. Tisha B'Av is a chasm on the calendar.
Americans must look at Sept. 11 on the calendar in much the same way Orthodox Jews see the ninth of Av. It is a hole in the year, a cataclysmic date on which the course of history changed.
For many Russians, Sept. 1 is such a date. It is the date, last year, when Chechen terrorists seized Beslan's Middle School No. 1, leading to a three-day siege and the massacre of 331 people, most of them children.
Americans will now also look at Aug. 29, the date Katrina roared ashore, as yet another hole in the year. As it did one year ago and four years ago, history tragic history is unfolding as summer draws to an end.
Last month, the New York City Fire Department added to our understanding of part of that history when it released 12,000 pages of transcripts of radio calls and oral statements from firefighters and paramedics describing the events of Sept. 11, 2001.
"Somebody yelled something was falling," reads the statement of firefighter Maureen McArdle-Schulman. Actually, it's more of a confession.
"We didn't know if it was desks coming out. It turned out it was people coming out, and they started coming out one after the other. We didn't know what it was at first, but then the first body hit and then we knew what it was. I was getting sick. I felt like I was intruding on a sacrament. They were choosing to die and I was watching them and shouldn't have been. So me and another guy turned away and looked at a wall and we could still hear them hit."
On Sept. 1, HBO premiered a devastating documentary about the Beslan massacre. "Children of Beslan" is a heartbreaking recollection of the siege by its youngest victims.
How can children make sense of events that adults can barely comprehend? Starved and thirsty, threatened constantly and cruelly with death, they recall drinking urine in desperation, seeing bodies explode and hoping that Harry Potter would save them with his invisibility cloak.
Of all the agonizing stories of the past two weeks, one painful story reported by the Associated Press from the Superdome humanized the suffering as much as any other. A young boy bound for Houston wailed as a police officer took away his dog. No pets were allowed on the bus. "Snowball," he cried over and over, until he vomited.
In time, perhaps, such dates Sept. 11, Sept. 1, Aug. 29 so closely grouped on the calendar will merge in popular culture into some transcendent day of mourning.
For now, the grief is too great, the pain from each too distinct. And perhaps that is one underlying motive of Tisha B'Av.
The human ability to do evil often appears to be unbounded. Our capacity for sorrow, on the other hand, is limited. If we can bind up all the terrible things in life on one single day, the remainder of the year in some sense becomes bearable.
There is another possible motive. We owe the dead our reverence the men and women who perished in burning buildings, the children shot in a gymnasium, the people drowned in the storm. But our grief must not be allowed to consume the rest of our days and immobilize us from the duty to the living.