What's an eruv?

Sitting around the Erev Shabbat table with some friends recently, my wife observed the connection between the mitzvah to observe the Sabbath and the deliverance from Egypt.  Specifically, she noticed the following line in the Erev Shabbat kiddush:

כי הוא יום תחילה למקראי קודש, זכר ליציאת מצרים.
For this [Shabbat] is the foremost of the holy days,
a remembrance of the exodus from Egypt.
(Az Yashir Moshe: A Book of Songs and Blessings)

We started talking about the connection between deliverance from slavery and the institution of a day of rest.  Then one friend raised a good question: when God first commanded Israel to observe the Shabbat, how did they know what the word Shabbat meant (and consequently how to keep it)?

Someone pointed out that the Torah actually does give details to the Israelites about what it means to observe the Shabbat: things like not doing any melakha (Exodus 31:12-17), not kindling fires (Exodus 35:3), and not leaving your place (Exodus 16:29).  That last command ("Remain each of you in his place; let no one go out of his place on the seventh day.") might be less familiar in our Messianic circles.  However, in Jewish tradition it became the foundation for the halakha of the eruv.  Historian David Rotenstein has the background:

Blues guitarist Buddy Guy frequently tells interviewers that when you stretch a string, you are stretching a life. When Orthodox Jews stretch a string to build an eruv, they are creating a community. Eruv is a Hebrew word and in English it means “to mingle.” An eruv is symbolic space created by Orthodox Jews to enable them to carry and push things on the Sabbath as they move around their neighborhoods and travel to and from synagogue. (Mapping MoCo's Jewish Courtyards -- the Eruvim (Updated)).

Also notable to Messianic Jews is the mention of this commandment in the Acts 1:12 reference to "a Sabbath day's journey."

For a more humorous take on the eruv (and a contemporary controversy over erecting one in West Hampton, Long Island), here's the Daily Show's hard-hitting investigative reporter Wyatt Cenac:

The Daily Show
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(HT: Rabbi Jason.)

While this video ends up being a commentary on the sad irony occurring when people from the same religion can't agree, it's even more ironic that the object of controversy is something which was originally intended to help promote community -- by creating a shared "place" where everyone can congregate.  To me, this is the real value of the eruv: it helps us to think more deeply about what it means to be in community and challenges us to observe the Shabbat in more holistic ways.

(Finally, for more on the connection between Yetziat Mitzrayim and Shabbat, check out Rabbi Joshua Flug's article in YUTorah's Pesach-to-Go 5771.)