Pliny the Elder [1st century CE] (Natural History, Book 10, 26-29): Geese keep careful watch; the cackling of geese warned of an attack at the Capitol in Rome. Geese may have the power of wisdom, as shown by the story of a goose who was the companion of the philosopher Lacydes and refused to leave his side. Geese are valued for their liver, which is a great delicacy, and for their feathers, especially the soft inner down. Geese come on foot to Rome from Gaul; if one gets tired it is moved to the front, so that it is forced to continue by the press of the geese behind it. Medicine can be made by mixing goose fat with cinnamon in a bronze bowl, covering it with snow and letting it steep. Only the ostrich reaches a greater size than the goose. Geese kept in a fishpond lose their flavor, and stubbornly hold their breath until they die.

Saint Ambrose [4th century CE] (Hexameron, Book 5, chapter 12.44): Who does not marvel at the nightly sentry watches of the. geese, who give evidence of their vigilance by their constant cackling? That was the way in which they defended even the Roman Capitol from the Gauls. You, Rome, rightfully owe to them the preservation of your empire. Your gods were sleeping, but the geese were awake. - [Savage translation, 1961]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 7:52): The duck gives its name to the goose [anser] by derivation, either from their resemblance, or because it too is frequently swimming. The goose bears witness to its vigils at night with persistent honking. No other animal is as sensitive to the smell of humans as is the goose; whence the ascent of the Gauls to the Capitolium in Rome was discovered from the noise of the geese. - [Barney, Lewis, et. al. translation]

Hugh of Fouilloy~> [ca. 1100-1172 CE] (De avibus, chapter 51): The goose makes known the watches of the night with the constancy of its cry. Moreover, no animal smells the odor of man as does the goose. Whence, by its cry, the ascent of the Capitoline Hill by the Gauls was discovered. Hrabanus says, "This [bird] can symbolize cautious men and those very anxious about their own safety." There [are] two varieties of geese, that is to say, the tame and the wild. The wild ones fly aloft and in an order, and denote those who, far from worldly affairs, preserve an order of righteous living. The domestic ones, however, live together in the villages; they cry out frequently; they tear at themselves with their beaks. They signify those who, even though they love the monastery, have time nevertheless for loquaciousness and slander. All wild geese are ashen in color, nor did I see any of them variegated or snowy. On the tame ones, however, are not only an ashen color, but also variegated or white. On the wild ones there is an ashen color, that is, on those [men] who have retired from the world is the unassuming garment of penitence. But those who live in the towns or villages wear clothing of more beautiful color. The goose more than other animals smells the scent of an approaching man, because the discerning man recognizes others, even at some distance, by good and bad report. Therefore, when at night the goose smells the scent of an approaching man, it continually cries out, because when the discerning brother sees in others the negligence of ignorance, he should cry out. Once upon a time the cry of the goose was helpful to the Romans on the Capitoline (Capitolio); and daily in the chapter (capitulo) the cry of the discerning brother is helpful when he sees negligence. The cry of the goose drove the Gallic enemy back from the Capitoline, but the cry of a discerning brother drives the Ancient Enemy from the chapter. The cry of the goose kept the Roman city free from the attack of the enemy; the cry of the discerning brother guards the community from being disturbed by the wayward. Perhaps Divine Providence would not give us the natures of birds unless It wished them to be helpful to us in some way. - [Clark translation, 1992]

Gerald of Wales [c. 1146 – c. 1223] (Topographia Hibernica, chapter 18): We may add to the list of birds a smaller species of white geese, also called gantes (wild geese), which are wont to arrive in great flocks, with a prodigious cackling. But they seldom migrate to these remote regions, and when they do, in very small numbers. The larger species, called by the vulgar bisiae, and also grisiae, come over in the depth of winter in vast flocks, when the north wind blows, and after the frosts are past, return with the south wind at the season for building their nests. - [Forester translation, 1863]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Birds 5.8): Geese or auce, as he says [i.e. Liber rerum], are birds of the size of an eagle. Of these, those that are strong, and properly seek the freedom of the high air, are of a gray color. They fly like cranes in an orderly line. According to the blowing of the winds, either from the South or from the North, they direct their flights. When it is blowing north they head south, knowing that colder times are imminent. Except when they graze in the meantime, they hardly rest from flying. For flight is so delightful to them that they rarely sleep. But for domestic geese, flight is heavy, feeding is most important, and resting and sleeping are most important. The hours of the night are ended at the crowing of a rooster. It is also said that their clamor betrays thieves, and this because no animal, as Isidore says, so quickly senses the scent of a man. And indeed it is found in the histories of the Romans, that on one occasion, when the guards of the Capitol had been oppressed by sleep and the enemy had surrounded the Capitol and endeavored to ascend, a goose raised the guards in the middle of the night by the cry of its voice, and thus delivered the citadel of the Capitol from danger. Basil the Great and Ambrose: You must therefore give merit to the goose, Rome, as you reign; your gods were sleeping, but the geese were watching. That is why you sacrifice geese on those days, and not to Jupiter. For your gods yield to geese, by which they know that they are defended lest they themselves should be taken by the enemy. Pliny: Geese were so perpetually attached to Lacides the philosopher, so that they never wished to be separated from him night or day in public or in secret. Geese give birth in the water, they mate in the spring or, if they are accustomed to mate in the winter, after the solstice. The most eggs are sixteen, the fewest are seven. If someone steals them, the eggs will hatch unless they are broken. They do not exclude foreign ones. When incubating it is most best for them to have nine or eleven. For their chicks contact with the stinging nettle is deadly. A remedy for nettles is the root of the plant. Sometimes they lay eggs without mating, but the are eggs do not produce chicks, as Aristotle says. They hiss to protect their chicks, as the Experimentator says. One of their chicks, which are not yet strong, is always on the lookout with an erect neck, lest the predatory eagle should come from above. They distinguish between an eagle and a vulture, which, of course, is difficult for man. They live for many years. The Egyptians say that they have geese with them, which have lasted since the time of Pharaoh. The strength of the light which is in the Sun injures the sense of the eyes most of all, and it cannot stand longer without corruption, unless - as is said of eagles - nature's deficiency is to some extent rejuvenated. But we never read that the nature of the goose is renewed. White geese are more fertile, variegated or brown geese less so, as Palladius says, because they have passed from the wild race to the domestic. Their meat is hard to digest. They bathe more frequently against the rain. Commage is a kind of goose, as Pliny says, the fat of which, in an earthen vessel with cinnamon, covered with much snow and freezing cold, is good for a most excellent medicine, which is called Commagum. There is another kind of goose, which, except for ostriches, is the largest among birds, but so heavy that it can be held down by the hand, motionless on the ground, and this especially in the later stage of life, when it has grown old. This species breeds in the mountains of the Alps and in the northern region, where it is rarely seen by humans. - [Badke translation/paraphrase]