XIV. What is our quarrel and dispute with both? To us there is One God, for the Godhead is One, and all that proceeds from Him is referred to One, though we believe in Three Persons. For one is not more and another less God; nor is One before and another after; nor are They divided in will or parted in power; nor can you find here any of the qualities of divisible things; but the Godhead is, to speak concisely, undivided in separate Persons; and there is one mingling of Light, as it were of three suns joined to each other. When then we look at the Godhead, or the First Cause, or the Monarchia, that which we conceive is One; but when we look at the Persons in Whom the Godhead dwells, and at Those Who timelessly and with equal glory have their Being from the First Cause—there are Three Whom we worship.
XV. What of that, they will say perhaps; do not the Greeks also believe in one Godhead, as their more advanced philosophers declare? And with us Humanity is one, namely the entire race; but yet they have many gods, not One, just as there are many men. But in this case the common nature has a unity which is only conceivable in thought; and the individuals are parted from one another very far indeed, both by time and by dispositions and by power. For we are not only compound beings, but also contrasted beings, both with one another and with ourselves; nor do we remain entirely the same for a single day, to say nothing of a whole lifetime, but both in body and in soul are in a perpetual state of flow and change. And perhaps the same may be said of the Angels and the whole of that superior nature which is second to the Trinity alone; although they are simple in some measure and more fixed in good, owing to their nearness to the highest Good.
XVI. Nor do those whom the Greeks worship as gods, and (to use their own expression) dæmons, need us in any respect for their accusers, but are convicted upon the testimony of their own theologians, some as subject to passion, some as given to faction, and full of innumerable evils and changes, and in a state of opposition, not only to one another, but even to their first causes, whom they call Oceani and Tethyes and Phanetes, and by several other names; and last of all a certain god who hated his children through his lust of rule, and swallowed up all the rest through his greediness that he might become the father of all men and gods whom he miserably devoured, and then vomited forth again. And if these are but myths and fables, as they say in order to escape the shamefulness of the story, what will they say in reference to the dictum that all things are divided into three parts, and that each god presides over a different part of the Universe, having a distinct province as well as a distinct rank? But our faith is not like this, nor is this the portion of Jacob, says my Theologian. But each of these Persons possesses Unity, not less with that which is United to it than with itself, by reason of the identity of Essence and Power. And this is the account of the Unity, so far as we have apprehended it. If then this account is the true one, let us thank God for the glimpse He has granted us; if it is not let us seek for a better.
XVII. As for the arguments with which you would overthrow the Union which we support, I know not whether we should say you are jesting or in earnest. For what is this argument? Things of one essence, you say, are counted together, and by this counted together, you mean that they are collected into one number. But things which are not of one essence are not thus counted…so that you cannot avoid speaking of three gods, according to this account, while we do not run any risk at all of it, inasmuch as we assert that they are not consubstantial. And so by a single word you have freed yourselves from trouble, and have gained a pernicious victory, for in fact you have done something like what men do when they hang themselves for fear of death. For to save yourselves trouble in your championship of the Monarchia you have denied the Godhead, and abandoned the question to your opponents. But for my part, even if labor should be necessary, I will not abandon the Object of my adoration. And yet on this point I cannot see where the difficulty is.
XVIII. You say, Things of one essence are counted together, but those which are not consubstantial are reckoned one by one. Where did you get this from? From what teachers of dogma or mythology? Do you not know that every number expresses the quantity of what is included under it, and not the nature of the things? But I am so old fashioned, or perhaps I should say so unlearned, as to use the word Three of that number of things, even if they are of a different nature, and to use One and One and One in a different way of so many units, even if they are united in essence, looking not so much at the things themselves as at the quantity of the things in respect of which the enumeration is made. But since you hold so very close to the letter (although you are contending against the letter), pray take your demonstrations from this source. There are in the Book of Proverbs three things which go well, a lion, a goat, and a cock; and to these is added a fourth;—a King making a speech before the people, to pass over the other sets of four which are there counted up, although things of various natures. And I find in Moses two Cherubim counted singly. But now, in your technology, could either the former things be called three, when they differ so greatly in their nature, or the latter be treated as units when they are so closely connected and of one nature? For if I were to speak of God and Mammon, as two masters, reckoned under one head, when they are so very different from each other, I should probably be still more laughed at for such a connumeration.
Source: Orations (New Advent)