Sir 48:17

“What it says in this passage, "He dug a canal in the rock with iron and built cisterns for water," mysteriously indicates the holy city, of which it is written, "The Savior is our fortified city," which cannot remain hidden since it is built on a hill. Elsewhere it is also written, "The rush of the river gladdens the city of God," and, "Marvelous things are said of you, city of God." He founded it and fortified it. And the Father says, "He built my city" and restores all the walls—which were in part knocked down by the malice of the pagans or of the heretics—with correct faith and true religion, raising the towers of the virtues and putting another wall without, a bulwark. In the building of forts these are called parapets, and they teach us to hold on to the efficacy of good works. It is not enough in fact to have the wall of faith, if this faith is not reinforced by good works. This wall and this bulwark are in fact made of living stones, which, according to the prophet, turn on the earth. The king made every kind of armor and shield, establishing the various testimonies of Scripture and commanding the evangelical doctrine in defense of his church. He established doctors who would lead the spiritual warriors and guide all the armies in a just and reasonable way, adequately defending the church's camps against every enemy.”