From the book of Marcus Varro, entitled, Of the Race of the Roman People, I cite word for word the following instance: "There occurred a remarkable celestial portent; for Castor records that, in the brilliant star Venus, called Vesperugo by Plautus, and the lovely Hesperus by Homer, there occurred so strange a prodigy, that it changed its color, size, form, course, which never happened before nor since. Adrastus of Cyzicus, and Dion of Naples, famous mathematicians, said that this occurred in the reign of Ogyges." So great an author as Varro would certainly not have called this a portent had it not seemed to be contrary to nature. For we say that all portents are contrary to nature; but they are not so. For how is that contrary to nature which happens by the will of God, since the will of so mighty a Creator is certainly the nature of each created thing? A portent, therefore, happens not contrary to nature, but contrary to what we know as nature. But who can number the multitude of portents recorded in profane histories? Let us then at present fix our attention on this one only which concerns the matter in hand. What is there so arranged by the Author of the nature of heaven and earth as the exactly ordered course of the stars? What is there established by laws so sure and inflexible? And yet, when it pleased Him who with sovereignty and supreme power regulates all He has created, a star conspicuous among the rest by its size and splendor changed its color, size, form, and, most wonderful of all, the order and law of its course! Certainly that phenomenon disturbed the canons of the astronomers, if there were any then, by which they tabulate, as by unerring computation, the past and future movements of the stars, so as to take upon them to affirm that this which happened to the morning star (Venus) never happened before nor since. But we read in the divine books that even the sun itself stood still when a holy man, Joshua the son of Nun, had begged this from God until victory should finish the battle he had begun; and that it even went back, that the promise of fifteen years added to the life of king Hezekiah might be sealed by this additional prodigy. But these miracles, which were vouchsafed to the merits of holy men, even when our adversaries believe them, they attribute to magical arts; so Virgil, in the lines I quoted above, ascribes to magic the power to
"Turn rivers backward to their source,
And make the stars forget their course."
For in our sacred books we read that this also happened, that a river "turned backward," was stayed above while the lower part flowed on, when the people passed over under the above-mentioned leader, Joshua the son of Nun; and also when Elias the prophet crossed; and afterwards, when his disciple Elisha passed through it: and we have just mentioned how, in the case of king Hezekiah the greatest of the "stars forgot its course." But what happened to Venus, according to Varro, was not said by him to have happened in answer to any man's prayer.
Let not the sceptics then benight themselves in this knowledge of the nature of things, as if divine power cannot bring to pass in an object anything else than what their own experience has shown them to be in its nature. Even the very things which are most commonly known as natural would not be less wonderful nor less effectual to excite surprise in all who beheld them, if men were not accustomed to admire nothing but what is rare. For who that thoughtfully observes the countless multitude of men, and their similarity of nature, can fail to remark with surprise and admiration the individuality of each man's appearance, suggesting to us, as it does, that unless men were like one another, they would not be distinguished from the rest of the animals; while unless, on the other hand, they were unlike, they could not be distinguished from one another, so that those whom we declare to be like, we also find to be unlike? And the unlikeness is the more wonderful consideration of the two; for a common nature seems rather to require similarity. And yet, because the very rarity of things is that which makes them wonderful, we are filled with much greater wonder when we are introduced to two men so like, that we either always or frequently mistake in endeavoring to distinguish between them.
But possibly, though Varro is a heathen historian, and a very learned one, they may disbelieve that what I have cited from him truly occurred; or they may say the example is invalid, because the star did not for any length of time continue to follow its new course, but returned to its ordinary orbit. There is, then, another phenomenon at present open to their observation, and which, in my opinion, ought to be sufficient to convince them that, though they have observed and ascertained some natural law, they ought not on that account to prescribe to God, as if He could not change and turn it into something very different from what they have observed. The land of Sodom was not always as it now is; but once it had the appearance of other lands, and enjoyed equal if not richer fertility; for, in the divine narrative, it was compared to the paradise of God. But after it was touched [by fire] from heaven, as even pagan history testifies, and as is now witnessed by those who visit the spot, it became unnaturally and horribly sooty in appearance; and its apples, under a deceitful appearance of ripeness, contain ashes within. Here is a thing which was of one kind, and is of another. You see how its nature was converted by the wonderful transmutation wrought by the Creator of all natures into so very disgusting a diversity, -- an alteration which after so long a time took place, and after so long a time still continues. As therefore it was not impossible to God to create such natures as He pleased, so it is not impossible to Him to change these natures of His own creation into whatever He pleases, and thus spread abroad a multitude of those marvels which are called monsters, portents, prodigies, phenomena,  and which if I were minded to cite and record, what end would there be to this work? They say that they are called "monsters," because they demonstrate or signify something; "portents," because they portend something; and so forth.  But let their diviners see how they are either deceived, or even when they do predict true things, it is because they are inspired by spirits, who are intent upon entangling the minds of men (worthy, indeed, of such a fate) in the meshes of a hurtful curiosity, or how they light now and then upon some truth, because they make so many predictions. Yet, for our part, these things which happen contrary to nature, and are said to be contrary to nature (as the apostle, speaking after the manner of men, says, that to graft the wild olive into the good olive, and to partake of its fatness, is contrary to nature), and are called monsters, phenomena, portents, prodigies, ought to demonstrate, portend, predict that God will bring to pass what He has foretold regarding the bodies of men, no difficulty preventing Him, no law of nature prescribing to Him His limit. How He has foretold what He is to do, I think I have sufficiently shown in the preceding book, culling from the sacred Scriptures, both of the New and Old Testaments, not, indeed, all the passages that relate to this, but as many as I judged to suffice for this work.
 See the same collocation of words in Cic. Nat. deor. ii. 3.  The etymologies given here by Augustin are, "monstra," a monstrando; "ostenta," ab ostendendo; "portenta," a portendendo, i.e. præostendendo; "prodigia," quod porro dicant, i.e. futura prædicant.
 The etymologies given here by Augustin are, "monstra," a monstrando; "ostenta," ab ostendendo; "portenta," a portendendo, i.e. præostendendo; "prodigia," quod porro dicant, i.e. futura prædicant.