Tisha B'Av, the ninth day of Av — this year commemorated on Saturday night and Sunday, Aug. 9 and 10 — marks the day on which a host of national tragedies befell the Jewish people. It is on Tisha B'Av that the First and Second Temples were destroyed and that the Jews were expelled from Spain.

All grieving — whether by an individual mourning the loss of a loved one or a community lamenting a national tragedy — has certain elements in common. Part of the grieving process is a nagging guilt that something could, or should, have been done differently to avert disaster. Often, our guilt is misplaced because some tragedies are inevitable despite everyone's best efforts.

On the other hand, some tragedies are not inevitable. For example, Jewish tradition holds that on the ninth of Av, 12 spies returned from surveying the land of Canaan. Ten bore unfavorable reports. Had these 10 maintained their trust in God and not instigated rebellion among Jews in the desert, the Jewish nation would not have been condemned to years of rootless wandering.

On Tisha B'Av, we are reminded that calamity arose because our ancestors did not heed the prophets' words. While those leaders predicted doom, they also provided a message of hope — if only people would listen and change.

Clearly, tragedy cannot always be avoided. But in those instances when we can already see the danger signs and where we still have an opportunity to respond, we have an obligation to do so. Tisha B'Av is an ideal time to heed modern-day prophets while planning strategies for preventing future calamities.

Unfortunately, we don't have to look far to discover contemporary threats to Jewish survival. As new data continues to show decreasing levels of Jewish identification, low levels of Jewish education, high intermarriage rates and general apathy toward Jewish commitment, we confront an enormous challenge. To ignore this danger is to deny the importance of Jewish continuity. It would be a tragedy of the highest magnitude if the Jewish community was no longer able to contribute its unique voice and special gifts to the nations of the world.

In fashioning a response to this crisis, the Jewish community has so far made a number of mistakes. Perhaps our largest error has been to focus almost exclusively on motivating our children — tacitly ignoring Jewish adults' right to share equally in our heritage's rich benefits. By not demanding the adult population's personal commitment, we collude in sending our children a very negative message, implying that a person's connection to Judaism diminishes with age. Little wonder that our youth do not feel compelled to choose Judaism for themselves.

An adult's decision not to work at strengthening his or her Jewish identity is not just a personal matter. It affects the entire community. Tisha B'Av is a time to reflect on this situation and to choose small, concrete ways in which we can each grow Jewishly in order to enrich our own lives while providing our children with Jewish memories. Thus we can ensure Jewish continuity.

Threats to Jewish survival take many forms. While loss of identity is among the most virulent, we must also guard against the weakening of traditional Jewish ideals and values.

The once-clear line separating church and state in this country has become increasingly blurred, while, the "Jewish agenda" — demanding social justice, compassion and concern for all human beings — is under constant attack. These threats, both political and spiritual, cannot be ignored, and on Tisha B'Av, we might consider how to address them.

Whether we respond with social activism or renewed educational efforts, we must act forcefully to preserve those social systems that manifest our core beliefs.

A second Jewish value in danger of disappearing is derekh eretz, proper manners, civility in public discourse. Tisha B'Av is a particularly appropriate time to recall the rabbinic dictum that the Second Temple was destroyed partly as a result of pointless hatred (sinat hinam) among the Jews.

Today, we are once again witnessing such hatred as — ironically — the Jewish community grows increasingly polarized over an issue that should unite us: a shared desire for peace and a real concern for the state of Israel. Instead, Jews with differing views on the peace process resort to name-calling and even threats of violence — all of which clearly violates Jewish teaching and threatens the fabric of the entire community. It is entirely fitting that on Tisha B'Av, Jews find areas of common ground in order to avoid repeating the tragedies of the past and to hasten the real peace for Israel and for the entire Jewish community.

Tradition maintains that after grieving, we must renew our strength and continue our lives. The period of shiva is finite; we are not permitted to mourn forever. In this spirit, let us use the holiday of Tisha B'Av to strengthen both our commitment and our community so that we can lessen, if not totally eliminate, the need for future mourning.

The writer is the executive vice president of the United Synagogue of Conservative Judaism, the association of Conservative congregations in North America.