Preface, Explaining His Design in Undertaking This Work.
The glorious city of God is my theme in this work, which you, my dearest son Marcellinus, suggested, and which is due to you by my promise. I have undertaken its defence against those who prefer their own gods to the Founder of this city—a city surpassingly glorious, whether we view it as it still lives by faith in this fleeting course of time, and sojourns as a stranger in the midst of the ungodly, or as it shall dwell in the fixed stability of its eternal seat, which it now with patience waits for, expecting until “righteousness shall return unto judgment,” and it obtain, by virtue of its excellence, final victory and perfect peace. A great work this, and an arduous; but God is my helper. For I am aware what ability is requisite to persuade the proud how great is the virtue of humility, which raises us, not by a quite human arrogance, but by a divine grace, above all earthly dignities that totter on this shifting scene. For the King and Founder of this city of which we speak, has in Scripture uttered to His people a dictum of the divine law in these words: “God resists the proud, but gives grace unto the humble.” But this, which is God's prerogative, the inflated ambition of a proud spirit also affects, and dearly loves that this be numbered among its attributes, to
Show pity to the humbled soul,
And crush the sons of pride.
And therefore, as the plan of this work we have undertaken requires, and as occasion offers, we must speak also of the earthly city, which, though it be mistress of the nations, is itself ruled by its lust of rule.
Source: City of God (New Advent)