Investing new meaning and relevance in old traditions is one of the challenges of the observant Jew. Few days are more challenging than Tisha Be’av.Walking around Jerusalem today one is struck by the beauty of the city, the bustling crowds that populate its streets, its liveliness. What does this Jerusalem have in common with the desolate city described in the Book of Lamentations and in Tisha Be’av liturgy? Never before in history have so many Jews lived in Jerusalem.Never before have Jewish sovereignty and political autonomy been so complete and vigorous. Never before have the Jewish people’s military might and political alliances afforded so much security.Economically, the State of Israel is dynamic and full of promise. Its hi-tech sector is world-renowned. Its standard of living places Israel on par with other developed Western countries. And unlike other Western countries, Israel’s population is growing briskly.Walking the streets of Europe, one is struck by the dearth of children and teenagers. Negative population growth has become the norm, seeming to reflect a general lack of optimism and unwillingness to invest in the future. Israel, in contrast, has a thriving younger generation. Families are larger than any other Western nation, reflecting the Jewish state’s vitality.If the rebuilding of the Temple is to be understood not as the actual brick and mortar construction of an edifice in which animals are once again sacrificed on an altar and a priestly class reinstituted to its cultic duties, rather as the Jews’ return to sovereignty in a burgeoning, revitalized state, perhaps we have already arrived.From this perspective, continuing to fast today is an act of ingratitude, a refusal to recognize and be thankful for events such as the ingathering of the exiles, the return of Jewish sovereignty and the religious freedom to adhere to all of God’s commandments in the Land of Israel. These are developments which Jews have been praying will materialize for nearly two millennia. Now that they have taken place, it is a slap in the face to God not to acknowledge them. Some try to resolve the tension between tradition and reality by re-imaging Tisha Be’av as a day of sadness for all the bad things that have happened to the Jewish people over the long centuries of exile: the expulsion of the Jews from Spain in 1492; the establishment of the ghetto for Rome’s Jews in 1555; Khmelnytsky’s massacre of Polish and Ukrainian Jewry in 1648.In this take, Tisha Be’av is a day of collective mourning for Jews’ past suffering and a realization that Jews continue to be a target of violent hatred. It is a day mourning the circumstances of the establishment of the State of Israel, which was delayed long enough to prevent the rescue of European Jewry from the Holocaust. Fasting and prayer are directed at the hope for a better era in which egregious hatred of Jews (and other “outsiders”) passes from the world. Skin color, religion, ethnicity or other labels used to classify groups as the hated other will no longer be used as a pretext for war, destruction and genocide.Tisha Be’av can also be a day for introspection as Jews living in a sovereign Jewish state with many imperfections.One of the positive aspects of messianic yearning bequeathed to the Western world by Judaism is its refusal to reconcile itself to injustice, inequality and other social ills. This world is not perfect. We must strive to fix its distortions and bring about tikkun olam.On the national level, this means reducing the huge gaps in Israeli society between the rich and the poor; combating the tendency toward balkanization of different groups: religious and secular, Arab and Jewish, Ashkenazi and Sephardi.The tension between celebration and mourning is difficult to maintain, but Jews are no strangers to dialectic.Tisha Be’av is at one and the same time a day of celebration as well as a day of mourning. It is anachronistic to commemorate Jerusalem’s physical destruction, when we should be celebrating its resurgence. However, we must also strive to right the many wrongs that continue to plague the world and Israeli society and acknowledge that the task of rebuilding Jerusalem is not yet over.