When he moved in 2014 from an apartment in Brooklyn’s Prospect Heights to a house he could afford in nearby Crown Heights, Naftali Hanau, a 37-year-old Orthodox Jewish businessman, suddenly found that, even in a secular and tolerant place like Brooklyn, the rigorous tenets of his faith now made it impossible for him to take his toddler son along to synagogue on the Sabbath.
Talmudic law derived from biblical commandments forbids doing 39 kinds of work on the Sabbath. In addition to plowing and harvesting, buying and selling, cooking by kindling a fire, writing and other obvious kinds of employment, carrying any object outside the home — keys, books, prayer shawls, canes or even babies — is forbidden. Pushing a stroller or wheelchair in public on the day of rest is also prohibited.
There is a significant loophole, however, that was developed millenniums ago by the Talmudic sages in Babylon as a way of making the biblical law compatible with the practical necessities of living and honoring the Sabbath as a day to delight in. It is known as an eruv — the Hebrew term for an artificial boundary enclosing an area and demarcated by existing walls, buildings and fencing with gaps filled in by wire, or, in modern times, translucent fishing line strung between lampposts and utility poles. According to the sages, an eruv extends the private domain of a home into the streets.
