Babylonian Talmud, Bava Batra 7b

Mishna: [A resident of a building located on courtyard] may be forced [by the other residents] to [contribute to] the building of a guardhouse and doors for the courtyard. Gemara: This would seem to show that a guardhouse is an improvement. Yet how can this be, given that there was a certain pious man with whom [the prophet] Eliyahu used to converse until he (the man) built a guardhouse, after which [Eliyahu] did not converse with him any more? [In other words, the man appears to have done something wrong because Eliyahu stops talking to him. But this seems to contradict the first text, which implies that building a gatehouse must be something good to do since residents can be compelled to help build one. ] There is no contradiction: in the one case [where Eliyahu stops talking to the man and therefore building the gatehouse must have been wrong] we suppose the guardhouse is inside [the courtyard]. [But in the other case, where residents must help build the gatehouse, it must be the case that] the gatehouse was built on the outside [of the courtyard]. Or, if you like, I can [explain away the apparent contradiction by] saying that in both cases we suppose the guardhouse to be outside, and still there is no difficulty, because in the one case [where the gatehouse is a societal good] there is a door and in the other [where Eliyahu disses the man] there is no door. Or, if you like, we may suppose that in both cases there is a door, and still there is no difficulty, because in the one case there is a latch [on the door] and the other there is no latch. Or, if you like, I may say that in both cases there is a latch and still there is no difficulty, because in the one case the latch is inside and in the other outside.