Every Shabbat morning at my synagogue in Los Angeles, some 700 people come together to celebrate and sing. In their voices are echoes of the emptiness of the synagogues of their past, in Iran, in Russia, in Poland and in other places where communities still exist but won’t for much longer. My congregants’ grandparents were a worldwide chorus.

Years ago, an American rabbi told me once he met an old man in Pruzhany, Belarus, who said he was the childhood teacher of the prominent scholar and philosopher Joseph Soloveitchik. “I am surprised to meet someone in a place so far away,” the rabbi told him. The man answered sadly: “It didn’t used to be so far away. This place used to be very close.”

In places that were once close, they now have caretakers instead of congregants. There are no pilgrims, only tourists. No prayers, only pictures. In Hebrew, a synagogue is called not a house of God, but a house of gathering. But there are none left to gather.

The flourishing of Jews in Israel and America is a proud story, often told. The destruction of Jews in the Holocaust is a tragic one, even more often told and commemorated and mourned. But there is also the slow slipping away in once great communities all over the world, with each child who leaves for the big city or another country or simply no longer cares, the loss of a thousand cultural legacies once borne by an ancient, scattered people.

And yet. The Jewish philosopher Simon Rawidowicz once titled an essay “Jews, the Ever-Dying People.” He wrote that each generation believes it is the last. In my travels I’ve come to understand that sadness is essential, but despair is a sin. Spain may be a land of ghosts, but it was not hard for me to find Jews with whom to celebrate the Passover Seder.

In Spain there will be Seders for those who seek one, and in the former Soviet Union there are new Jewish summer camps and schools. In Budapest, traveling with the Joint Distribution Committee, I met with young Jews who learned of their heritage in their teens and 20s from dying grandparents who had survived the Nazis and the Communists. They were eager to learn who they really were. In Sweden I taught young Jews. And across Europe, even amid a resurgent anti-Semitism, there are proud Jews eager to reclaim what has been lost.

Throughout Jewish history the “ner tamid,” the eternal light, has gone out. But it has also been relit. All those empty synagogues wait; all those unopened books and unsung words retain their meaning. We are rekindling people.

On Friday night, the ritual of the Seder will be enacted in once forgotten corners all over the world. Doors will be opened for Elijah that had long been closed. And newcomers will sit beside the ghosts to tell the story once more.