A new perek (#6), a new mishnah... What happens when there's no possibility of carrying, even given the hope of an eruv hatzerot. One who lives on the same courtyard as a non-Jew (or a Samaritan or a Sadducee), none of whom accept the rabbinic authority that establishes eruv, cannot be active sharers of space when it comes to eruv. Alternatively, the problem isn't the one Jew among other non-Jews, but when there are more than on Jews among the non-Jews. Plus a race to declare "ownership" over that area - between the Jews and the non-Jews. The presence of the non-Jews is a definite wrinkle. Is the residence of a non-Jew considered a halakhic residence? [Who's Who: Abaye bar Avin, not to be confused with Abaye.] A clear concern about establishing norms of a high level of comfort between Jews and non-Jews. Some of the phrasing here is less than pleasant for modern ears, for which the mix of Jews and non-Jews is so accepted. [What's What: The 7 Mitzvot of the Noahides; also: Megilat Taanit] What are we doing when we set up an eruv? Also: Can a student issue a halakhic decision that differs from that of his teacher? We know we're going to pasken according to R. Eliezer ben Yaakov, but Abaye's question is whether one can do so, even if we usually would not - specifically when it comes to this situation of Jews and non-Jews living in proximity, and the way it has impact on eruv. Which means the question of how each generation will function in the absence of the previous one, and the key elements of understanding halakhah as case by case, perhaps nowhere more exemplified than in Hilkhot Eruvin.