Beda Venerabilis
Jerusalem was situated on a gentle incline, oriented towards the north-east, which allowed rainwater to flow freely rather than pool, streaming through the eastern gate and replenishing the Kidron in the valley of Jehoshaphat, while carrying away the debris from the streets. It seems likely that the Dung Gate served as the main passage for removing the refuse. Equally important and beneficial is the act of clearing away all that is impure from the Lord's city as it is to preserve all that is pure within it. Those who construct the Dung Gate in Jerusalem represent those who establish within the holy Church a ministry that purges the minds of the faithful from the filth of vice, ensuring that the corrupt are kept outside the community of believers. The rain of divine grace supports this effort, washing away all impurities, allowing, as the Psalmist notes, those who commit iniquity to be rooted out from the presence of the Lord (Psalm 100:8).