Etymologiae, Book III, chapters 67-71: De stellis planetis to De nominibus stellarum, quibus ex causis nomina acceperunt
Chapter LXVII. On the planets Certain stars are called planets, that is, wanderers, because they run about through the whole world with varied motion. Hence, because they wander, they are said to be retrograde, or are made irregular, that is, when they add and subtract small parts. But when they only subtract, they are called retrograde; and they make a station when they stand still.
Chapter LXVIII. On the precession and forward motion of the stars The precession or forward motion of the stars is when a star seems to carry out its motion and goes somewhat ahead contrary to custom.
Chapter LXIX. On the withdrawal or retrogradation of the stars. The withdrawal or retrogradation of the stars is that in which a star, while it carries out its motion, seems at the same time to be moved backward.
Chapter LXX. On the standing of the stars The standing of the stars is that whereby, though a star is always moving, it nevertheless seems to stand in some places
Chapter LXXI. On the names of the stars, and for what reasons they received their names The sun (sol) is so called because it appears alone (solus), all the other heavenly bodies being darkened by its brilliance. The moon (luna) is so called as if it were Lucina, the middle syllable being removed. Of her Virgil says: “Chaste Lucina, favor us.” She took her name by derivation from the light of the sun, because she receives light from it and gives back what she has received. The stars (stellae) are named from standing (stare), because, being fixed, they stand always in heaven and do not fall. For the stars that we see seeming to slip from heaven are not stars, but little fires fallen from the aether; these occur when the wind, seeking higher regions, draws the fire of the aether along with it, and by its trail imitates falling stars. For stars cannot fall: they are immovable, as was said before, and are borne fixed with heaven. The heavenly bodies (sidera) are so called because sailors, by considering them (considerando), direct the counsel of their course, lest they be led elsewhere by treacherous waves or winds. Certain stars are called signs because sailors observe them in guiding the oars, contemplating their keenness and brilliance, by which the future state of the sky is shown. But all men also look to them to foresee the qualities of the air through summer and winter and the temperature of spring. For by their rising or setting at fixed stations they signify the quality of the seasons. The first of the signs is Arcton, which, fixed on the axis, wheels with seven stars revolving in itself. The name is Greek, and in Latin it is called the Bear; and because it turns in the manner of a wagon, our people have called it the Septentrio. For triones are properly plough oxen, so called because they tread (terere) the earth, as if teriones. And the nearness of the axis causes the Septentriones not to set, because they are on it. Arctophylax is so called because he follows Arcton, that is, the Bear Helice. They have also called him Bootes, because he is attached to the wagon: a sign conspicuous for its many stars, among which is Arcturus. Arcturus is a star placed behind the tail of the Great Bear, in the sign of Bootes. Hence it is called Arcturus, as if “the bear’s tail,” because it is situated in the breast of Bootes. It rises in the autumn season. Orion shines in the south before the footsteps of the Bull, and Orion is named from urine, that is, from the flooding of waters. For rising in the season of winter, it troubles the sea and the lands with waters and storms. The Latins call him Iugula, because he is armed like a sword, and is terrible and very bright with the light of his stars; if all these shine in him, fair weather is foretold; if their keenness is dimmed, a storm is seen to be threatening. The Hyades are named from “to rain,” that is, from moisture and rains. For rain in Greek is called hyetos. By their rising they bring rains. Hence the Latins also called them suculae, because when they rise, the signs of rains are shown. Of them Virgil says: “Arcturus and the rainy Hyades.” They are seven, in the forehead of the Bull, and they rise in the spring season. The Pleiades are named from plurality, because the Greeks call plurality pleiston. For there are seven stars before the knees of the Bull, of which six are seen, for one is hidden. The Latins call them Vergiliae from the signification of the season, which is spring (ver), when they rise. For by their setting they show winter, by their rising summer, and the time of the first sailing.
The Dog-star, which is also called Sirius, is in the middle of the center of heaven in the summer months; and when the sun has ascended to it, its heat, joined with the sun, is doubled, and bodies are dissolved and steamed. Hence from this star the days are called dog days, when purgings also are troublesome. It is called the Dog either because it afflicts bodies with disease, or on account of the whiteness of its flame, which is of such a kind that it seems to shine beyond the rest. And so, to make it better known, they called it Sirius. The comet is a star so called because it pours forth from itself locks (comae) of light. When this kind of star appears, it signifies either pestilence, or famine, or wars. Comets are called in Latin crinitae, because they scatter flames in the manner of hair; the Stoics say that there are more than thirty of them, whose names and effects certain astrologers have written. Lucifer is so called because among all the heavenly bodies it bears the most light; and it is one of the planets. It is also properly called iubar, because it pours forth a mane (iuba) of light, but the splendor of the sun and moon and stars too is called iubar, because their rays stretch out in the manner of a mane. Vesper is a western star, which they say took its surname from Hesperus, king of Spain. It too is one of the five planets, leading on the night and following the sun. It is said that this star, rising, makes the morning star, and setting, the evening star. Of it Statius says: “And one is weighed in the alternate rising.” The planets are stars that are not fixed in heaven like the rest, but are borne in the air. They are called planets from plane, that is, from wandering. For sometimes they are borne to the south, sometimes to the north, for the most part against the world, sometimes with the world. Their Greek names are Phaethon, Phaenon, Pyrion, Hesperus, Stilbon. The Romans consecrated them to the names of their gods, that is, of Jupiter, Saturn, Mars, Venus and Mercury. For, deceived and wishing to deceive, in flattery of those who had given them something out of love, they pointed out stars in heaven, saying that that star was Jupiter’s and that one Mercury’s: and an opinion of vanity was conceived. The devil confirmed this opinion of error; Christ overthrew it. Now as for those which the pagans themselves call signs, in which the image of living creatures is formed from stars, such as Arcton, Aries, Taurus, Libra and others of the kind: those who surveyed the heavenly bodies, moved by superstitious vanity, imagined a bodily shape in the number of the stars, fashioning both the images and the names of their gods from certain causes. For they named Aries, the first sign, to which, as to Libra, they assign the middle line of the world, after Jupiter Ammon, on whose head those who make idols fashion the horns of a ram. The pagans set this sign first among the signs because in the month of March, which is the beginning of the year, they say the sun runs its course in this sign. They also place Taurus among the stars, and this too in honor of Jupiter, because in the fable he was changed into a bull when he carried off Europa. Castor and Pollux also they set after death among the best known stars: this sign they call Gemini. They called Cancer so because when the sun comes to this sign in the month of June, it goes backward in the manner of a crab, and makes the days shorter. For this animal has an uncertain front part, and finally directs its step to either side, so that the front is the back and the back the front. Hercules killed a huge lion in Greece, and for his valor set it among the twelve signs. When the sun touches this sign, it gives the world exceeding heat, and makes the yearly Etesian winds. They placed the sign of the Virgin also among the stars for this reason, that in the same days in which the sun runs through it, the earth, scorched by the burning of the sun, brings forth nothing. For this is the time of the dog days. They called Libra from the equality of that month, because on the 7th day before the Kalends of October the sun, running through that sign, makes the equinox. Hence Lucan also says: “To the weights of the just balance.” Scorpio and Sagittarius also they named on account of the lightning of that month. Sagittarius is a man deformed with the legs of a horse, to whom they attach an arrow and a bow, that by this the lightnings of that month might be shown. Hence he was also called Sagittarius. The figure of Capricorn they fashioned among the stars on account of the she-goat, Jupiter’s nurse; the hinder part of whose body they formed in the likeness of a fish, to designate the rains of the same season, which that month usually has toward its end. Further, they named Aquarius and the Fish from the rains of the seasons, because in winter, when the sun is carried through these signs, heavier rains are poured out. And wonderful is the madness of the pagans, who have transferred to heaven not only fishes but also rams and he-goats and bulls, bears and dogs and crabs and scorpions. For the eagle and the swan too, on account of the fables of Jupiter, they placed among the stars of heaven in memory of him. Perseus also and his wife Andromeda, after they died, they believed to have been received into heaven; so that they marked their images with stars, and were not ashamed to call them by their names. The Charioteer also, Erichthonius, they placed among the stars of heaven, because they had seen that he first yoked four-horse chariots. For they marveled that his ingenuity had come near to the imitation of the Sun, and for this reason set his name among the stars after his death. So Callisto, daughter of King Lycaon, when she had been violated by Jupiter and in the fable changed by Juno into the shape of a bear, which in Greek is called arktos, after her killing Jupiter translated her name, with her son, among the northern stars, and called her Arcton and her son Arctophylax. So the Lyre was placed in heaven for Mercury; so the Centaur Chiron, because he nursed Aesculapius and Achilles, was numbered among the stars. But in whatever manner of superstition these are named by men, they are nevertheless stars which God established at the beginning of the world and ordained to distinguish the seasons by a fixed motion. The observations of these signs, therefore, or nativities, or the other superstitious practices that attach themselves to the knowledge of the stars, that is, to the knowledge of the fates, are without doubt contrary to our faith, and ought to be so ignored by Christians that they may seem not even to have been written. But some, drawn by the beauty and brilliance of the stars, have fallen with blinded minds into the errors of the stars, so that by noxious calculations, which is called mathesis, they try to be able to foreknow the outcome of events: these not only the teachers of the Christian religion but even, among the pagans, Plato, Aristotle and others, moved by the truth of things, have condemned with one accord, saying that confusion of affairs is rather generated by such a persuasion. For if the human race were pressed to various acts by the necessity of birth, why would the good deserve praise, or the wicked incur the vengeance of the laws? And although they themselves were not devoted to heavenly wisdom, yet by the testimony of truth they rightly struck down their errors. This order of the seven secular disciplines was carried up by the philosophers as far as the stars, namely that they might lead minds entangled in secular wisdom away from earthly things, and set them in the contemplation of things above.