According to biblical law, once an area has been converted in to a reshut hayachid by enclosing it with a halachically acceptable eruv, one may carry inside the enclosed area. But according to rabbinical law, it is simply not enough to enclose an area in which one wants to carry with an eruv. This alone will not permit carrying from the home into the street or vice versa. Neither will it alone permit carrying from a condominium apartment into the lobby or other common areas.
The rabbis were concerned that if they permitted carrying from the private domain of the home into the public domain of the street – even when the area is enclosed by a properly constructed eruv – people might find themselves carrying from their homes into the street in the absence of an eruv enclosure.
In order to carry from the home into the street, the rabbis require an additional procedure called the “merging of streets” or shitufei mavo’ot. In order to carry from one’s apartment into the corridors or lobby of a condominium, an additional procedure called the “merging of courtyards” or eruvei chatzeirot is required. We shall refer to both shitufei mavo’ot and eruvei chatzeirot by the term eruvin.
The purpose of eruvin is to merge all homes, apartments and streets in the enclosed area into a single communal entity. After the eruvin ceremony has been performed, members of the communal entity are no longer considered to be carrying from private domains into public domains.
The two ceremonies of shitufei mavo’ot and eruvei chatzeirot can be conducted simultaneously by depositing bread or matzot in one designated home or synagogue on behalf of all Sabbath observers in the enclosed area. Because, according to halacha, a person lives where he eats, this symbolic gesture has the power to merge all residences in the enclosed area into one communal home.
When, the reader might ask, has one ever been invited to participate in this eruvin ceremony? The answer is that it is performed on one’s behalf, without one’s participation, by a member of the community eruv committee. This agency is based on the halachic principle that a benefit can be bestowed on one in one’s absence, zachin le’adam shelo befanav, on the assumption that everybody benefits from the ability to carry on Shabbat.
The committee agent performs the ceremony once each year, on erev Pesach, by placing a box of matzot on behalf of all the Sabbath observers in the designated home or in a synagogue. When so doing, the committee agent recites the blessing “Al Mitzvat Eruvin” and the eruvin becomes effective for all the Sabbaths of that year.
According to halacha, in order for the eruvin ceremony to be valid it must be performed on behalf of all owners of streets and homes in the enclosed area. This presents a problem because non-Jews and others who do not observe Shabbat are not eligible to participate in the eruvin ceremony. The solution is for the committee agent to enter into a token lease by which the non-Sabbath observant owners lease their streets and homes to the Sabbath observers for the sole purpose of allowing them to carry from their homes into the streets.