1 But whence has man this knowledge, and who has ministered these truths to mortal ears? Or whence has a tongue of flesh the power to speak of things so utterly distinct from fleshly or material substance? Who has gazed on the invisible King, and beheld these perfections in him? The bodily sense may comprehend elements and their combinations, of a nature kindred to its own: but no one yet has boasted to have scanned with corporeal eye that unseen kingdom which governs all things nor has mortal nature yet discerned the beauty of perfect wisdom. Who has beheld the face of righteousness through the medium of flesh? And whence came the idea of legitimate sovereignty and imperial power to man? Whence the thought of absolute dominion to a being composed of flesh and blood? Who declared those ideas which are invisible and undefined, and that incorporeal essence which has no external form, to the mortals of this earth?
2. Surely there was but one interpreter of these things; the all-pervading Word of God. For he is the author of that rational and intelligent being which exists in man; and, being himself one with his Father's Divine nature, he sheds upon his offspring the out-flowings of his Father's bounty. Hence the natural and untaught powers of thought, which all men, Greeks or Barbarians, alike possess: hence the perception of reason and wisdom, the seeds of integrity and righteousness, the understanding of the arts of life, the knowledge of virtue, the precious name of wisdom, and the noble love of philosophic learning. Hence the knowledge of all that is great and good: hence apprehension of God himself, and a life worthy of his worship: hence the royal authority of man, and his invincible lordship over the creatures of this world.
3. And when that Word, who is the Parent of rational beings, had impressed a character on the mind of man according to the image and likeness of God, and had made him a royal creature, in that he gave him alone of all earthly creatures capacity to rule and to obey (as well as forethought and foreknowledge even here, concerning the promised hope of his heavenly kingdom, because of which he himself came, and, as the Parent of his children, disdained not to hold converse with mortal men); he continued to cherish the seeds which himself had sown, and renewed his gracious favors from above; holding forth to all the promise of sharing his heavenly kingdom. Accordingly he called men, and exhorted them to be ready for their heavenward journey, and to provide themselves with the garment which became their calling. And by an indescribable power he filled the world in every part with his doctrine, expressing by the similitude of an earthly kingdom that heavenly one to which he earnestly invites all mankind, and presents it to them as a worthy object of their hope.
Source: Oration in Praise of Constantine (New Advent)