I was discussing my daf posts with my friend and colleague, Rabbi Matthew Liebenberg of Claremont Shul, Cape-Town, and he tried to warn me that keeping up the pace and variety of posts will be much more challenging when we get to Eruvin, which is known as a particularly complicated and technical masechta.

Though I could not deny that I share a degree of concern, I replied that Eruvin is actually one of my “favorite” tractates, assuming it is possible or appropriate to say such a thing. In addition to being filled with fascinating and extremely practical rules essential to understanding the practicalities of Eruv building, something almost all of us need to know, it also contains many general ideas and topics that apply to all of Torah holistically.

This combination of material typical of the Gemara can be found right here on the first daf as well.

The thrust of the first daf deals with the technical requirements for a quiet side-street or alley to be considered a private domain on Shabbos.

The typical neighborhood in the times of Chazal (as can still be seen in some older neighborhoods of Yerushalayim) consisted of a מבוי – a short and narrow side-street or alley which opened to the main public thoroughfare on 1 or 2 sides.

Various חצרות (courtyards) opened to this central מבוי and each courtyard had houses that opened to it.

מדאורייתא ( at a biblical level,) any area enclosed on 3 sides (the exact number of sides/partitions is subject to debate later) was considered a private domain, and carrying within it was permitted.

As such, as far as biblical law is concerned, it is permitted to carry from one house to another within the courtyard, from one courtyard to another within the common מבוי , or within the courtyards or מבוי , so long as the מבאי is only open on one side to the public domain.

If the מבוי is open on two sides to the public domain, it is more complex, as the מבוי itself could be considered part of it.

Our Mishna and sugya deals with a מבוי that is closed on 3 sides and only open on one side to the public domain.

We see later that there is a rabbinical requirement to symbolically mark or enclose such a מבוי with either a pole on one side, or a beam going from one side to the other (there is some debate about these precise requirements as well.)

Our Mishna focusses on the maximum height that this pole or beam may be, as well as the maximum width of the open side, and rules that if they are higher than 20 amos (arm-lengths/cubits) or wider than 10 amos respectively, they need to be lowered or narrowed.

Rabbi Yehuda disagrees and says there is no such requirement.

It is unclear from the Mishna whether Rabbi Yehuda holds that the fourth side can be of infinite height or width, or whether he too places a limit on this, but simply a higher or wider one, but it would seem that if the later is correct, one could have expected him to say what this limit is.

The Gemara notes that a similar maximum height is discussed regarding a Sukkah (Sukkah 2a,) but the language used there is different.

Whereas in our case, we are told that a מבוי that is too high needs to be lowered, regarding Sukkah, we are simply told that it is פסול (invalid.)

As in both cases, lowering it is both compulsory and effective, the difference in language needs to be explained, and the parallel sugya in sukkah asks the very same question and gives the very same answers.

Two answers are given :

1. Seeing as the Sukkah is דאורייתא (biblical,) the Mishna uses the word “invalid.” As the pole or beam of aמבוי are only rabbinical requirements, the mishna simply tells us the תקנתיה (solution.)
2. The later language is also appropriate in theory for the biblical requirement of Sukkah, but seeing as a Sukkah has multiple constraints, each requiring a different solution, the Mishna chooses one word that applies to all of them, for the sake of brevity. Rashi explains that this is based on the principle (Pesachim 3b) that one should always teach one’s students using concise language.

There are various approaches in the Rishonim as to how to understand the first answer.

Rashi seems to understand that when the Gemara contrasts the biblical Sukkah with the rabbinical מבוי , it is not referring to the actual requirement of dwelling in a Sukkah or putting a pole or beam on a מבוי, even though the distinction certainly applies to that as well, but to the maximum height of the Sukkah and the מבוי.

We derive the maximum height of a sukkah from a verse in the Torah: למען ידעו דורותיכם כי בסוכות הושבתי את בני ישראל (“So that your generations will know that I placed the Jewish people in sukkot” -Vayikra 23/43.)- the Sukkah has to be low enough for the roof to be noticed.

As such, this requirement predates the writing down of the mishna by far, and it is appropriate to say that it is already invalid.

In contrast, the requirement to mark a מבוי with a pole or a beam itself is only rabbinical and its maximum dimensions are also. Seeing as the Mishna is the first to teach us these maximum dimensions, it is not appropriate to label the מבוי as already invalid but only to tell us how to solve the issue from the beginning.

This explanation has various difficulties, but I shall not dwell on them in this post.

Tosfos understands the answer a little differently- Due to the strict biblical requirements of sukkah, we are concerned that using a softer language would make us think that the requirement to fix it up is only לכתחילה (in the first place,) but if one sat in the sukkah without making these corrections, one would fulfill the mitzva still בדיעבד (post-facto.)

As such, the harsher language is preferred.

In the case of Eruvin, seeing as the requirement is only rabbinical, we are less concerned that a person might make this error, and we choose to use the softer language, in keeping with the principle (Pesachim 3a) that it is always best to use לישנא מעליה (positive language ) where possible.

We see that there are 3 principles at work here, which sometimes need to be traded off against each other, and it is fascinating to note that both Rashi and Tosfos refer to the same sugya in Pesachim which discusses 2 of these principles and the trade-off between them, but for completely opposite purposes.

1. Language needs to be נקיה (clean), and that doesn’t just mean avoiding foul language but specifically choosing לשון מעליא (positive language.)
2. Language needs to be concise (probably to make it easier to comprehend and remember.)
3. Language needs to be clear or strong enough to convey the historical timeline of the law (Rashi) or the stringency of the law (Tosfos)

According to the first answer in the Gemara, the third factor over-rides the first factor, and strength of message over-rides the need for positive language.

According to the second answer in the Gemara, either positive language still takes priority over strength of message, or the positive language given is still considered appropriate or strong enough to give over the importance of the message.

However, the second factor certainly takes priority over the first, and concise direct language is preferred over positive language, as is indeed the conclusion of the above-quoted sugya in Pesachim.

There is lots more to say about the requirements for language to be clean, concise, and strong enough and how they trade-off with each other, but we have certainly seen on this first daf how the Gemara is able to focus on the one hand on specific and technical rules relating to the subject at hand, and at the same time teach us multiple principles that could apply to every aspect of our lives!

These posts are intended to raise issues and stimulate further research and discussion on contemporary topics related to the daf. They are not intended as psak halacha.