But even Goldstein has difficulty describing the notion of an eruv, an imaginary boundary--something like a safe zone in a kids' game of tag, a force field protecting the starship Enterprise. Orthodox Jews create such safe zones to allow the faithful to abide by the many rules of Shabbat without surrendering every convenience or, most gentiles would no doubt believe, necessity.

So to understand how an eruv works, Goldstein explains, one must know the many prohibitions of Shabbat--the seventh day of creation when, according to the Old Testament, God rested.

Goldstein grows so animated during the discussion of Shabbat traditions that his yarmulke slips from his head. He retrieves the prayer cap, pins it back onto his scant hair and continues.

Shabbat begins at sundown Friday with the lighting of candles and blessings over the candles, wine and challah, a braided Jewish bread. It ends at sundown Saturday, often with a Havdalah, a ceremony during which candles are lighted, wine is sipped and a spice box is passed around. All this is meant to separate Shabbat from other days and to ensure that the coming week will be a good one.

Goldstein looks forward to Shabbat all week long. He walks to the synagogue for a service on Friday evening, and to hear a passage from the Torah (the Old Testament) on Saturday morning. Shabbat is a time for introspection. Goldstein and his family sit around the dinner table and sing songs, and Goldstein debates principles of Jewish law with friends.

Yet for the truly devout Jew, observing the day of rest is a lot of work. Meals must be fully prepared before sundown Friday, as no electricity may be used. Fires cannot be lighted. Driving is prohibited. No sports. No gardening. No umbrellas: It is forbidden to erect a tent on Shabbat.

Even trivial conversation is taboo.
Most of these activities are defined in Hebrew as melacha--work--and are encompassed in 39 prohibited acts listed in the Book of Exodus.

"Let no man leave his place on the seventh day," Exodus commands. Jewish law interprets that as prohibiting the carrying of objects outside of the home.

In practical terms, this means David Goldstein can't carry his prayer book and prayer shawl when he walks to synagogue on Shabbat. His wife can't carry her reading glasses. The Goldsteins can't take a casserole to a potluck dinner or a bottle of wine to a friend's house.

The Goldsteins' fellow congregants with young children must stay put on Shabbat; they are not to carry a child or push a stroller outside the house. The same goes for a wheelchair.

Ah, but Jewish law is never that simple; there are many exceptions to the rules. Thousands of years ago, rabbis offered a solution to the schlepping dilemma, in the form of an eruv--a defined area where some of the most impractical rules of Shabbat are suspended.

The Hebrew word "eruv" (pronounced ay-ROOVE) is defined as "mixture, merging, amalgamation or blending of activities and rights." Goldstein explains that the word is closely related to erev, the Hebrew word for evening, the blending of day into night. An eruv blends public and private domains, allowing one to break certain rules of Shabbat while the celebrant is outside the home.

The first eruv took the form of a wall that King Solomon ordered built around Jerusalem. Remember, it's permissible to carry objects inside the home. The wall made the community into one great big home, in effect, and--mazel tov!--it was kosher to carry.

But people inside an eruv may do nothing beyond carrying, and may carry only the bare necessities--no money, no car keys, no pocketbooks, no newspapers. And still no umbrellas, those metaphoric tents.

The modern eruv incorporates existing boundaries--both natural and manmade--such as ravines and highways, supplemented with poles and wires that denote the boundary.

Most eruvin (plural for eruv) are all but invisible, unless you know what to look for. Although it incorporates some physical materials, the eruv exists mainly in the minds of those who believe in it. Chances are, you've been inside an eruv and never knew it. From Seattle, Washington, to St. Louis, Missouri, to Sydney, Australia, Orthodox Jews have erected eruvin.

The first eruv in the United States was probably created in Manhattan during the Fifties. The White House and Supreme Court sit inside the Washington, D.C., eruv. There are more than 100 eruvin in North America.

But none in Phoenix, until now.
David Goldstein, David Segal, Rabbi David Rebibo and a handful of other Orthodox Jews (not all of them named David, by the way) are in the process of constructing an eruv in north central Phoenix. In so doing, Phoenix will become one of the last major metropolitan centers in the U.S. to have an eruv.