Rabbi Zakkai quotes a baraita in the presence of Rabbi Yohanan which rules that the area at the entrance to the Mavoy (alleyway) – under the cross beam or between the side posts (see 5a-b) – would be considered a karmelit (i.e. a place in which carrying would be Rabbinically forbidden).
Rabbi Yohanan reacts strongly to this baraita, saying “Pok T’nai L’vara” – go and teach that baraita outside! In other words, Rabbi Yohanan does not accept the baraita as it was presented to him; he believes that carrying would be permitted. This expression indicates that Rabbi Yohanan did not merely disagree with the ruling; he felt that it was incorrect to such an extent that it should not be taught and discussed in the Beit Midrash (study hall). On occasion, we find in the Gemara that an amora chooses to privately pursue an avenue of study outside the Beit Midrash that is not accepted as part of the discourse inside the Beit Midrash. On a practical level, that is what is being suggested here, aside from the clear statement that we do not consider this opinion when deciding the halakha.
The Gemara then brings a difference of opinion between Rava and Abaye.
Abaye said: Rabbi Yohanan’s statement is reasonable with regard to the area beneath the cross beam, as only the area beneath the cross beam should be considered a private domain, but between the side posts, carrying is indeed prohibited, in accordance with the opinion of Rabbi Zakkai. And Rava said: The entire statement of Rabbi Zakkai is to be rejected, as Rabbi Yohanan asserted, and even in the area between the side posts carrying is permitted.
Abaye argues that only part of the baraita was rejected, and while under the cross beam (kora) one would be permitted to carry, it would be forbidden to carry between the side posts (lehi). Rava believes that the entire baraita was rejected and that, in both cases, Rabbi Yohanan permits carrying.
In an attempt to explain his position, Abaye brings a number of statements which seem to indicate that the ruling with regard to “between the lehis” would forbid one to carry (i.e. they have the halakhic status of a karmelit). Rava responds to each case by explaining that the ruling was only true because the Mavoy opened into a karmelit, and the area abutting the karmelit gets the status from its neighbor. In a case where the Mavoy opens to a Reshut ha-Rabim (public domain), however, then the area between the lehis would retain the status of a Mavoy.
In response to Rava’s explanation, the Gemara responds “Yatziva be-Ar’a, v’Giyora bishmei shemaya!?” (literally – A permanent resident is down on the ground, while a stranger is raised up to the highest heavens?). The expression means that things seem to be the opposite of the way they are presented. In our case, it seems odd that we would be more stringent in the matter of a Rabbinic decree (the karmelit) than in the matter of a Biblical law (the Reshut ha-Rabim). Similarly, it seems unreasonable that the stranger (the Ger) should be considered to be on a higher level than the citizen.
This expression is a translation (with a slight variation) of a passage from the tokhaha (the chapter of rebuke) that appears in Sefer Devarim (28:44). The passage reads “the stranger among you will rise above you higher and higher, and you will fall lower and lower.” The idea here is that we are shocked and surprised to find a situation that is the opposite of what we expect.
Rava’s response is “Matza min et mino v’nei’or” – similar subjects find each other and are awakened. Since the Mavoy is a Rabbinic decree, when it comes into contact with a karmelit it can take on the characteristics of a karmelit. When it comes into contact with a Reshut ha-Rabim, however, it cannot take on the characteristics of a full public domain, so it remains a Mavoy in which it is permissible to carry.