Rabbinic law must strike a balance between leniencies and stringencies, between necessary religious limits and a certain permissiveness that enables observant Jews to live reasonable lives. And the eruv is a perfect example of that balance. An eruv allows a somewhat freer observance of Shabbat, but it is predicated on a highly restrictive law that considers carrying even a small item in public on Shabbat to be forbidden labor. Even as the rabbis entertain various ways to ease the burden of such laws, they are mindful to uphold the strictures of the law itself.
An example of this is found in the mishnah on today’s daf, which describes a scenario in which a town loses its residents and becomes a private town. Think of a small neighborhood that might be bought and owned by its residents. The mishnah teaches:
If a public city loses residents over time and becomes a private city, one may not establish an eruv for all of it unless one maintains an area outside the eruv that is like the size of the city of Ḥadasha in Judea, which has 50 residents.
According to the mishnah, a city that becomes private cannot encircle its entire area with an eruv unless it leaves an area equivalent in size to the city of Hadasha outside the eruv. Why? According to Rashi, leaving a part of a town uncovered by the eruv serves an important public education function. One day the city could become a larger public one again and we wouldn’t want people to forget the rules of eruv. Leaving a small area uncovered by the eruv ensures that people will notice that the whole reason they are permitted to carry at all is because of the eruv.
No wonder the name of the town the mishnah cites is Hadasha, which means “new.” With a part of the town uncovered by the eruv, the laws of eruv will always remain a new and fresh topic of conversation.
This kind of thing is actually still done today. Once a year, the community of Elizabeth, New Jersey, declares its eruv to be inoperative, a custom initiated by Rabbi Pinchas Teitz to educate the community about the general rule that carrying is forbidden on Shabbat. Otherwise, people raised in Elizabeth carrying within the eruv on Shabbat might not realize that this action is permitted only because of the eruv.
In other words, loopholes only work if we still remember the original law it was before the loophole. The eruv only works as a way of expanding Jewish law if we live by Jewish law in the first place. Our mishnah reminds us that sometimes it pays to leave a little room for Jews to remember both the leniency and the stringency, the expansiveness and the limitation. It is right in the middle of that balance that meaningful religious life can be found.