The Approach of R. Johanan and Caesarea's Judges to the Issue of a Round Window (Eruvin 76a-b)


  • Uri Zur
  • David Garber


Eruvin, round window, R. Johanan, Caesarean judges, Rabbanan de-Kissarei


The Mishna in Bavli Tractate Eruvin (7:1) refers to a square shaped window that has the effect of joining two courtyards for the purpose of eruv hatzerot (courtyard eruv). A sugya that relates to the Mishna brings the statement of R. Johanan on the topic of a round window. This statement is the basis for a discussion in the sugya, which parallels the discussion on the topic of a sukkah in the form of a furnace (Sukkah 7b-8b). From the conclusion of the sugya in Eruvin it appears that the words of R. Johanan are explained following the method of the Caesarean religious judges (or the Caesarean Rabbis).

The purpose of this article is to examine the different explanations given for R. Johanan's statement, as well as the problems arising from these explanations, and to try and reach a conclusion as to whether R. Johanan made a mathematical error, as thought by some of the commentators, or whether his words contain no mathematical error and they can be construed as mathematically correct, as explicated by other commentators.



How to Cite

Zur, U., & Garber, D. (2024). The Approach of R. Johanan and Caesarea’s Judges to the Issue of a Round Window (Eruvin 76a-b). BDD, 37, 59. Retrieved from



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