Guests are invited to our sukkah, some of whom are alive and some of whom are historical. The Ushpizin, biblical characters who traditionally visit the sukkah, remind us that we all live in two communities.

There is a horizontal community. They are our contemporaries, who surround us: family and friends, teachers, work associates and even those whom we watch or listen to and help shape our opinions about the world. Our horizontal community has the advantage of being immediate and alive; it has the disadvantage of limitation — you can only choose it from people who happen to be upright when you are.

The vertical community is composed of historical figures from every age. Here you can choose from centuries. Your guide might be a biblical character, a rabbi from the Talmud, a chasidic teacher of the 19th century — anyone whose legacy of learning speaks to you. The Ushpizin remind us that we do not only live in space, we live in time. If you don’t know the past, you are parochial, stuck in the years you happen to be alive. Study those who went before, travel in time and your community becomes boundless.

Rabbi David Wolpe is spiritual leader of Sinai Temple in Los Angeles. Follow his teachings at www.facebook.com/RabbiWolpe.