Rav Yehuda says: All of the city’s residents must contribute to the building and upkeep of the city gates [le’aglei gappa], and for this purpose money is collected even from orphans. But the Sages do not require protection and are therefore exempt from this payment. All of the city’s residents must contribute to the digging of cisterns [lekarya patya], and for this purpose money is collected even from the Sages, since they too need water. The Gemara comments: And we said this only when the people are not required to go out en masse [be’akhluza] and do the actual digging, but are obligated merely to contribute money for that purpose. But if the people are required to go out en masse and actually dig, the Sages are not expected to go out with them en masse, but rather they are exempt from such labor.