Sources : Eagle

Bible (Latin Vulgate, Psalm 102:5): "Renovabitur sicut aquilae iuventus tua" (Your youth will be renewed like the eagles); (NIV, Psalm 103:5) " youth is renewed like the eagle's". It is believed that this phrase is the origin of the theme of the eagle renewing its youth, since this idea is not found in ancient literature.

Aristotle [ca. 350 BCE] (De animalibus Book 9, 2.3; 9, 22.4; 9, 23.3): [Book 9, 2.3] The eagle and the dragon are enemies, for the eagle feeds on serpents. [Book 9, 22.4] When eagles grow old, their beaks become more and more curved, so that at last they die of famine. [Book 9, 23.2] ...for when the eagle turns out its young, the phene [fene, bearded vulture] takes them up and feeds them; for the eagle ejects them before the proper time, when they still require feeding, and are unable to fly. - [Cresswell translation, 1887]

Lucan [1st century CE] (Pharsalia, Book 6, verse 799-800; 9, verse 1057-1061): [Book 6, verse 799-800] "...stones / That sound beneath the brooding eagle's wings...". [Book 9, verse 1057-1061]: So the bird of Jove / Turns his new fledglings to the rising sun / And such as gaze upon the beams of day / With eves unwavering, for the use of heaven / He rears; but such as blink at Phoebus' rays / Casts from the nest."

Pliny the Elder [1st century CE] (Natural History, Book 10, 3-6): [Book 10, 3] Of the birds known to us the eagle is the most honorable and also the strongest. Of eagles there are six kinds. The one called by the Greeks the black eagle, and also the hare-eagle is smallest in size and of outstanding strength; it is of a blackish color. It is the only eagle that rears its own young, whereas all the others, as we shall describe, drive them away; and it is the only one that has no scream or cry. Its haunt is in the mountains. To the second kind belongs the white-rump eagle found in towns and in level country; it has a whitish tail. To the third the morphnos, which Homer also calls the dusky eagle, and some the plangos and also the duck-eagle; it is second in size and strength, and it lives in the neighborhood of lakes. ... Next, the fourth class comprises the hawk-eagle, also called the mountain stork, which resembles a vulture in having very small wings but exceeds it in the size of its other parts, and yet is unwarlike and degenerate, as it allows a crow to flog it. It is always ravenously greedy, and keeps up a plaintive screaming. It is the only eagle that carries away the dead bodies of its prey; all the others after killing alight on the spot. This species causes the fifth kind to be called the 'true eagle', as being the genuine kind and the only pure-bred one; it is of medium size and dull reddish color, and it is rarely seen. ... The species that we made the third hunts round marshes for water-birds, which at once dive, till they become drowsy and exhausted, when it catches them. The duel is worth watching, the bird making for refuge on the shore, especially if there is a dense reed-bed, and the eagle driving it away from the shore with a blow of its wing; and when it is hunting its quarry in a lake, soaring and showing its shadow to the bird swimming under water away from the shore, so that the bird turns back again and comes to the surface at a place where it thinks it is least expected. ... Often even the eagles themselves cannot carry the weight of their catch and are drowned with it. The sea-eagle only compels its still unfledged chicks by beating them to gaze full at the rays of the sun, and if it notices one blinking and with its eyes watering flings it out of the nest as a bastard and not true to stock, whereas one whose gaze stands firm against the light it rears. ... Some people add a species of eagle which they call the bearded eagle, but which the Tuscans call an ossifrage. [Book 10, 4] The three first and the fifth kinds of eagle have the stone called eagle-stone (named by some gagites) built into their nests, which is useful for many cures, and loses none of its virtue by fire. The stone in question is big with another inside it, which rattles as if in a jar when you shake it. But only those taken from a nest possess the medicinal power referred to. They build their nests in rocks and trees, and lay as many as three eggs at a time, but they shut out two chicks of the brood, and have been seen on occasion to eject even three. They drive out the other chick when they are tired of feeding it: indeed at this period nature has denied food to the parent birds themselves as a precaution, so that the young of all the wild animals should not be plundered; also during those days the birds' talons turn inward, and their feathers grow white from want of food, so that with good reason they hate their own offspring. But the chicks thrown out by these birds are received by the kindred breed, the bearded eagles, who rear them with their own [also said of the coot]. However the parent bird pursues them even when grown up, and drives them far away, doubtless because they are competitors in the chase. And apart from this a single pair of eagles in order to get enough food requires a large tract of country to hunt over; consequently they mark out districts, and do not poach on their neighbors' preserves. When they have made a catch they do not carry it off at once, but first lay it on the ground, and only fly away with it after first testing its weight. They meet their end not from old age nor sickness but from hunger, as their upper mandible grows to such a size that it is too hooked for them to be able to open it. They get busy and fly in the afternoon, but in the earlier hours of the day they perch quite idle till the market-places fill with a gathering of people. If eagles' feathers have the feathers of any other birds mixed with them, they swallow them up. It is stated that this is the only bird that is never killed by a thunderbolt; this, is why custom has deemed the eagle to be Jupiter's armor-bearer. [Book 10, 5] The first and second kinds not only carry off the smaller four-footed animals but actually do battle with stags. The eagle collects a quantity of dust by rolling in it, and perching on the stag's horns shakes it off into its eyes, striking its head with its wings, until it brings it down on to the rocks. Nor is it content with one foe: it has a fiercer battle with a great serpent, and one that is of much more doubtful issue, even though it is in the air. The serpent with mischievous greed tries to get the eagle's eggs; consequently the eagle carries it off wherever seen. The serpent fetters its wings by twining itself round them in manifold coils so closely that it falls to the ground itself with the snake. - [Rackham translation]

Aelianus [170-230 CE] (On the Characteristics of Animals, Book 1, 42; 2, 26; 2, 40): [Book 1, 42] Among birds the eagle has the keenest sight. ... And the eagle is said to serve not himself alone but to be good for men's eyes as well. At any rate, if a man whose sight is dim mix an eagle's gall with Attic honey and rub it on his eyes, he will see and will acquire extremely keen sight. [Book 2, 26] At no time does the eagle need water or long for a dusting-place; he is on the contrary superior to thirst and looks for no medicine for weariness from any outside source, but scorning water and repose he cleaves the atmosphere and gazes with piercing eye from the vast expanse of heaven on high. And at the mere sound of those rushing wings even that most intrepid of all creatures, the great serpent, dives at once into its den and is glad to disappear. And this is the way in which the eagle tests the legitimacy of his young ones. He plants them, while they are still tender and unfledged, facing the rays of the sun, and if one of them blinks, unable to endure the brightness of the rays, it is thrust out of the nest and banished from that hearth. If however it can face the sun quite unmoved, it is above suspicion and is enrolled among the legitimate offspring, since the celestial fire is an impartial and uncorrupt register of its origin. [Book 2, 40] The eagle is apparently the most jealous guardian of its young. At any rate if it sees anyone approaching them, it does not allow him to depart unpunished, for it beats him with its wings and lacerates him with its talons; and the punishment it inflicts is moderate, for it does not use its beak. - [Scholfield translation]

Saint Ambrose [4th century CE] (Hexameron, Book 5, 18.60-61): [Book 5, 18.60] It is generally stated in treatises dealing with the eagle that she, too, abandons her young. This is true, however, only of one out of two nestlings. Some have thought this situation arose from a reluctance to bring up a twin brood. But this is hardly worthy of credence, especially since Moses has given us such convincing testimony on the devotion of this bird to her young when he said: 'As the eagle protects his nest and inspires trust in his nestlings: hovering over them, he spreads his wings and hath taken them and carried them on his shoulders. The Lord alone led them. How, then, did he spread his wings over his young if he killed one of them? For this reason I think that this bird does not act cruelly from a desire to refrain from giving nourishment. Rather, there is a question of making a decision. For it is agreed that the eagle tests the quality of her young, lest signs of degeneracy and deformity may cause deterioration in a species which affects the role of regal dominion over all birds. And so it is asserted that the eagle exposes her nestlings to the rays of the sun and suspends with her claws her young in mid-air. If one of them stays unruffled and unmoved, fearlessly facing the light of the sun as it strikes his eyes, he is approved. He has thus demonstrated the truth of nature by the steadiness of his unaffected gaze. The one, however, who turns away his eyes, 'dazzled by the sun's rays,' is rejected. He is deemed unworthy of such a parent, unfitted to be recognized as genuine offspring, and hence undeserving of support. The eagle does not therefore reject her young because of natural cruelty. This is, rather, the result of her soundness of judgment. There is no refusal of what is native, but rather a rejection of what is alien. [Book 5, 18.61] What some consider to be a disposition toward cruelty in such a royal bird is compensated by the kindly traits of a bird of lower caste. This bird, known as the waterfowl [coot] adopts the nestling of the eagle when disowned or not recognized and allows him to mingle with her own brood. She exercises over him the same maternal care as she does over her own, providing food and nourishment impartially.- [Savage translation, 1961]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 7.10-11): [Book 12, 7.10] The eagle [aquila] is named from the acuity of its vision [acumen oculorum], for it is said that they have such sight that when they soar above the sea on unmoving wings, and invisible to human sight, from such a height they can see small fish swimming, and descending like a bolt seize their prey and carry it to shore with their wings. [Book 12, 7.11] It is said that the eagle does not even avert its gaze from the sun; it offers its hatchlings, suspended from its talons, to the rays of the sun, and the ones it sees holding their gaze unmoving it saves as worthy of the eagle family, but those who turn their gaze away, it throws out as inferior. - [Barney, Lewis, et. al. translation]

Hugh of Fouilloy~> [ca. 1100-1172 CE] (De avibus, chapter 60): The eagle (aquila) is named for the sharpness (acumine) of its eyes; for it is said to be of such vision that when it is borne on motionless wing above the sea and is not accessible to human gaze, from such height it sees the little fish swimming, and descending like a missile, it drags off to the beach the prey seized on the wing. Now, it is said that [the eagle] maintains its gaze at the sun's ray, whence it exposes its chicks, held by a claw, to the rays of the sun. And it keeps as worthy of the species the one which it sees holding an immobile gaze. But if [it sees] any [chicks] turning their gaze away, [the eagle] rejects them as degenerate. Whence the blessed Gregory said, "By the word eagle in sacred Scripture is sometimes meant evil spirits, robbers of souls, sometimes powers of this world, or sometimes either the most subtle minds of the saints, or the incarnate Lord swiftly flying over the lowest regions and then seeking again the heights. By the eagles' name is represented waylayers of the spirit. It was the testimony of Jeremiah who said. Our persecutors were swifter than the eagles of the air (Lam. 4: 19). For our persecutors are swifter than the eagles of the air when evil men do such things against us that they appear to exceed those masters of the air in inventions of evil. Earthly power is symbolized by the word 'eagle.' Whence it is said by the prophet Ezekiel, A large eagle with great wings, long limbed, full of feathers, and of variety, came to Libanus and took away the marrow of the cedar and cropped off the top of the twigs thereof (Ezek. 17:3-4). Because surely who else does the eagle represent but Nebuchadnezzar, king of Babylon, who is described by the vastness of [the eagle's] great wings for the vastness of his army, by the length of its legs for the long duration of his life, as full of feathers for his truly great wealth, by rich color moreover for the boundless array of his worldly glory? [The bird] came to Libanus and took away the marrow of the cedar and cropped off the top of the twigs thereof, because, seeking the grandeur of Judea, [Nebuchadnezzar] removed the nobility of his kingdom, as though they were the marrow of the cedar; and while he brought down the tenderest offspring of the kings from the heights of their kingdom by taking them captive (4 Kings 24:14-16), it is as though [the eagle] plucked off the highest branch of the [cedar]. By the word 'eagle' the subtle discernment of the saints is represented, whence so likewise is the prophet [Ezekiel] while he described his vision of the four Evangelists in the form of animals (Ezek. 1:5-10). Among these it is the fourth animal, that is, the one symbolizing St. John, which left the earth in flight, because by subtle discernment [St. John] penetrated the innermost mysteries by comprehending the Word. Likewise, thy who still deliberately abandon worldly things, like the eagle and St. John seek heavenly things through contemplation. At the same time the blessed Gregory said of the eagle, Like the eagle flying to the prey (Job 9:26). It is, however, the custom of the eagle to look with unflinching gaze at the rays of the sun. But when it is impelled by the need of refreshment, it turns the same gaze that it fixed upon the sun's rays to the sighting of a corpse. And although it flies very high, it nevertheless seeks the earth in order to seize meat. Thus it is clear that the ancient fathers were similar, who to the extent that human frailties allowed, contemplated the light of the Creator with an upright mind. But with foreknowledge that He would be incarnate at the end of the world, they turned their eyes as it were from the sun's rays toward the earth, and come as if from the heights to the depths while they acknowledge God above all things, and [God made] Man within all things. While they perceive that He will suffer and die for human kind, by that death they know with certainty that they themselves will be renewed and reformed, just as, in the manner of the eagle, after contemplating the Sun's rays, they seek food in a Corpse. Put another way, like the eagle flying to the prey. For the eagle is lifted in very high flight, and with a nimble effort is poised on the upper air, but because of the wants of its belly it seeks the earth, and casts itself suddenly down from the heights. So thus humankind in the First Parent [Adam] fell from the heights to the depths, because his status in Creation was surely poised in the heights of reason as if in the freedom of the air. But because [he responded to] his belly's wants [and], contrary to [God's] order, seized food, he came to earth; and [now] he eats flesh as if after a flight, because he lost those free breezes of contemplation, and is enticed downwards by fleshly desires. Again concerning the eagle. Thy youth shall be renewed like the eagle's (Ps. 102:5). It is usually said about the eagle that when it is burdened by age, its beak becomes hooked, so that it is not able to eat, but becomes weak from thinness. Coming upon a rock, it sharpens its beak, and thus, eating again, it is rejuvenated. The rock is Christ, the eagle any righteous man who sharpens his beak on the rock while through good deeds he renders himself like unto Christ. - [Clark translation, 1992]

Gerald of Wales [c. 1146 – c. 1223] (Topographia Hibernica, chapter 9): These birds eye with fixed gaze the full effulgence of the solar rays; and it is reported that they teach their young to do the same, though unwilling. ... Thus, contemplative men strive to fix the whole powers of their mind without distractions on the very essence of the Divine majesty, and on the true sun of righteousness, and, putting their hands to the plough of the heavenly paradise, do not look backward. ... Eagles also live for so many ages, that, enjoying renewed youth, they seem to contend with eternity itself. So also the saints, renewed with the innocence of childhood, having put off the old man, and put on the new man, obtain the blessed fruit of everlasting life. Again, eagles often soar so high in their flight, that their wings are scorched with the fiery rays of the sun. So those who in the Holy Scriptures strive to unravel the deep and hidden secrets of the heavenly mysteries, beyond what is allowed, and those limits which it is not permitted us to pass, returning to themselves halt below as if the wings of the presumptuous imagination on which they were borne were scorched in their flight. - [Forester translation, 1863, chapter 9]

Letter of Prester John [ca. 1165-1170 CE] (paragraph 29-30): There are small gems there, which are called midriosi, and which eagles are often accustomed to bring to our country, by which they rejuvenate and restore their sight. If someone should wear one on his finger, his sight would not fail, and if his sight diminishes, it is restored, and the more he uses his eyes, the sharper his sight becomes.- [Michael Uebel, Translation of Original Latin Letter of Prester John]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Birds 5.2-3): [Birds 5.2] As Augustine says, the eagle is the most noble bird, being the king of birds. It is large, it lives on prey and meat. The sight of its eyes is so sharp and firm, that it can look at the sun's rays directly; whence it sits willingly turned towards the sun. It holds its chicks in the rays of the sun. When it sees them holding an unmoving gaze, it preserves and feeds them as if they were worthy of the race. But if it sees those who obstinately turn away, it casts them off as degenerates. Some thought, as Ambrose says, that this was done through a reluctance to care for the chicks. Which I do not think is to be believed, but rather by the examination of judgment, lest the deformity of in the birth of its kind should cause the eagle be disgraced among all the birds. But the eagle does not condemn the chick with the bitterness of nature, but with the integrity of its judgment, and does not renounce the chick as if it were its own, but as if rejecting it as a stranger. Yet this royal bird moderates the severity of its rejection of the unwanted bird and excuses it with clemency. For the bird whose name is the coot, which in Greek is called fene, takes up the chick that was abandoned and thrown out by the eagle and connects it with its offspring; and intermingling with its own, in the same way as it feeds and nourishes its own offspring with food. As Andelmus says, when the eagle is burdened with old age, it seeks the coldest spring, it flies over there on high and transcends all the clouds. At once it seeks the nest, and among the chicks, which are now strong enough to overcome the inequality of cold and heat, it takes off his feathers with a perspiration seized by a kind of fever, and is comforted by its chicks, and feeds, until it recovers its feathers. Augustine: Because the hook of its beak grows so excessively that it can hardly catch fish with effort, it strikes its beak with a stone in a natural way, shakes off the hook and repairs it so to be able to fish. Jacobus: It has a stone called ethitem in the nest, or, as some would say, a stone called jet which is useful for many remedies. It is said to have this stone so that eggs do not perish from too much heat; for the heat cannot harm the stone. Other philosophers also say, as the Experimentator relates, that the eagle places two precious stones called indes [Indian stone] in its nest, without whose presence it cannot endure. As the Liber Kyrannidarum says, above the eyes of the eagle in the eyebrows are two stones which are powerful against demons. If you put an eagle's beak to your head at night, you will dream whatever you want. As the Experimentator says, the eagle fasts many days, and teaches its chicks to lick blood. When it sits, it always looks at its claws, lest they become curved. The eagle shares its prey with other birds and allows the food to be eaten; but let them beware: if the fish being shared is not enough for it, it seizes one of the birds that are flying and eats it. A crow sometimes pursues an eagle, and when the eagle has long concealed itself, it finally seizes the crow with its talons. Aristotle says that the eagle generally has two young, and yet lays three eggs; but after it has hatched three, it throws down one, and thus fostered only two. It was seen, however, that an eagle sometimes had three chicks. But, as Aristotle says, this is not from three eggs; but the eagle brings out three chicks from only two eggs, two from one egg, one from the other. The feathers of eagles, as Pliny says, mixed with the feathers of other birds, do not, as if by some natural instinct, mix with them, but destroy them. The wings of the eagle are straight and extended, but curved at the top. This is not the case with all birds: Pliny says this with regard to eagles. The eagle has a larger right foot than the left. The eagle pursues its adult chicks, chasing them away as rivals, that is, by predation. They do not immediately carry off the plunder they have taken, but first put it down, and after trying the weight, they fly away with it according to their strength. Eagles fight with the stag, and they beat them with their feathers until they rush backward onto the rocks. On the other hand, deer throw a lot of dust into the eyes of eagles. The battle with the dragon is even fiercer for them. But where the dragon is strong, sometimes it binds the eagle's wings with multiple coils. It is the worst kind of eagle, which drives out its young before their time, from the fatigue of nursing them. As Aristotle says, that when it ages it is weakened to such an extent that it cannot hunt prey, and its claws are bent so that it cannot hold prey, and its feathers turn white and becomes so heavy that it can hardly fly. But there is another bird, which is naturally merciful and pious, which with pity shelters and feeds the abandoned chicks of strangers, and challenges them to the strength of flight. The eagle does not sit long on stones, lest the edge of its claws be blunted. The eagle builds its nest in the highest trees or rocks, where evil beasts cannot easily reach it. But if a dragon, or a man, or any beast, or bird, wishes to disturb or kidnap the eagle's young, it fights for them with wonderful courage, exposing itself to the danger of death. It is also said of the eagle that it has a certain premonition, so that, no matter how far it is from its chicks, it feels that the enemies of the chicks are coming. An eagle lifts its chicks on its shoulders to challenge them to flight. All noble birds fear the sight of the eagle, and lose their courage that day, and cannot easily fly to their prey. [Birds 5.3] The northern eagle is a large and grand bird, living in the north. This bird always lays two eggs, as Pliny says, in its nest suspended in the tops of the branches. And when it catches a hare or a fox, it strips off its skin little by little and wraps its eggs in that fur and lays them under the heat of the sun, and so it leaves his eggs and does not lay them down, but waits until they are broken at their natural maturity in the coming out of the young. Then first returning to the chicks, it feeds them until they are fully strong. - [Badke translation/paraphrase]

Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book12.1): Now it perteineth to speake of birds, and foules in perticular, and first of the Eagle, which hath principalitye among fowles. Among all manner kinds of diverse fowles, the Eagle is the more liberall and frée of heart, as Plinius saith. For the pray that she taketh, except it be for great hunger, shée eateth not alone, but putteth it forth in common to fowles that follow her: But first she taketh her owne portion and parte. And therfore oft other fowles follow the Eagles, for hope and trust to have some part of hir pray. But when the pray that is taken is not sufficient to her self, then as a king that taketh heed of a Comint, hée taketh the bird that is next to him, and giveth it among the other, and serveth them therewith. And she setteth in her neast two precious stones, which hée called Achates. The one of them is male, and that other female. And it is sayde, that they maye not bring foorth their birdes without those stones. And she layeth in her neast that precious stone that is called Achates, to kéepe her birdes from the venimous biting of créeping worms, as Plinius saith. And ye Eagle is called Aquila, and hath that name of sharpnesse of eien, as Isidore sayth. For she hath so strong, and so sharp, and cléere sight, (as it is sayde) that when shée is borne and flieth up into the aire, and hoveth above the Sea so high, that unneth shée is seene with mans sight. And out and from so great highnesse, shée séeth a smal fish swimme in the Sea, and falleth downe anone, as it were a stone, and taketh sodeinely the fish, and draweth the prays that is so taken sodeinelye to the cliffe. And is a Birde hotte and drye of kinde, and desireth prays, and is ryght strong, bolde, and hardye, passing the strength and boldnesse of other birdes, and his strength is most in wings, féete, and bill. For hée hath sinewye wings, and little flesh, and therfore in his flight hée may well awaye with travaile. For in comparison to the greatnesse of his bodie, he hath but little flesh, & therefore hée hath much strength and vertue. Also hée hath many feathers, and therfore he conteineth much lightnesse. And among all Fowles, in the Eagle the vertue of sight is most mightye and strong. For in the Eagle the spirit of sight is most temperate, and most sharpe in act and deede of séeing and beholding the Sunne in the roundnesse of his circle, without anye blemishing of eyen. And the sharpenesse of her sight is not rebounded againe with cléernesse of light of the Sunne, neither dispearpled, as Ambrose sayth. Also Ambrose sayth, and Aristotle libro. 20. that ther is one manner Eagle that he calleth Almachor, and is ful sharpe of sight, and shée taketh her owne birdes in her claws, and maketh them to looke even on the Sunne, and that ere their wings bée full growen, and except they looke stiflye and steadfastly against the Sunne: shée beateth them, and setteth them even before the Sunne. And if any eie of any of her Birdes watereth in looking on the Sunne, shée slaieth him, as though he went out of kind: or else driveth him out of the neast, and dispiseth him, and setteth not by him: and the birde that beholdeth and setteth his eie steadfastly uppon the Sun, she féedeth and loveth him as her owne birde, lyke to her in kinde: and though she sette her sight never so straight and steadfast on the Sunne, yet she casteth her eie to waite and espie after her praye, as Gregorye sayth. And Aristotle. libro. 12. sayth, that clove footed Birdes neede sharpe sight. For they see meate from a right farre place: & therfore the Eagle flieth higher then other fouler, and therfore she buildeth her neast in ful high rockes, there she maketh her neast sure, and defendeth it with highnesse of place, as Grego[ry] sayth. The Eagle dwelleth sure and safe in most high places, and neverthelesse because of meate shee looketh and seeth these lowe places: He flyeth highest upward, and commeth sodeinlye downewarde, when hee séeth a carrion, or some other pray, he desireth. Also the Eagle is a foule that seldome sitteth a broode, and seldome hath birdes, and nourisheth and féedeth her birds. Libro sexto Aristotle saith, yt the Eagle laieth thrée egges at the most, & throweth the third egge out of the neast: for she sitteth a brood heavylye theruppon. And he sayth furthermore, that at that time she is so much féebled, that she maye not well hunt birds of other foules: for then her clawes be crooked, & her wings waxe white, and then she is sore gréened in féeding of her birdes. And if it happeneth that ye Eagle hath thrée birds, she throweth out one of her neast, for difficulty of féeding and nourishing: But a bird that is called Ossifraga [the osprey; this tale is usually said of the coot], & is called Cebar in the language of Arabia, féedeth ye bird yt the Eagle casteth so haply out of her neast, as he sayth. Also he sayth, that there be diverse kinds of Eagles, & they feed diversly their birds: for Eagles with white tailes, travaile more in féeding of their birds, the¯ Eagles with black tailes, which travaile lesse in such dooing. And when her birds bée ready for to flye, shée putteth them out of her neast, and exciteth and comforteth them lyttle and little for to flye, and maketh them fast and to be hungry, for to have the more desire to come after her into the aire, because of meate. And if it happen that they bée slow to passe out of her nest, then she smiteth them with her bill, & withdraweth from them their meate, to constraine the¯ in that manner to passe out of the neast. And after that they be full in strength and in feathers, she driveth them awaie from her, and is no more busie aboute them, except one manner kinde of Eagles, that Aristotle calleth Athat, that thinke long time on her birds. And when her birds flye, she flyeth with them, and giveth them meate, and flyeth sometime about them, and taketh heede of them, and is ready to withstand other foules, if it so be that they come to grieve or to noy hir birds. Aristotle toucheth all this. li. 6. as Gregory toucheth super Job. It is said of the Eagle, that when hir young birds be newly hatcht: and unmightie to take & receive and defie great meat, then ye mother sucketh bloud, & fleeting humour out of her pray, & holdeth it in her mouth, and putteth the bloud and such humour to the mouthes of her birdes. And féedeth them so with lyght meat, till they bée strong and able to receive & take stronger meate. And héereto Austen saith and Plinie also, that in age the Eagle hath darknesse & dimnesse in eien, & heavinesse in wings. And against this disadvantage she is taught by kinde, to séeke a well of springing water, and then she flyeth up into the aire as farre as she may, till she be full hot by heat of the aire, and by travaile of flight, and so then by heate the pores be opened, & the feathers chased, and she falleth sodeinlye into the well, and there the feathers bee chaunged, and the dimnesse of her eien is wiped away and purged, and she taketh againe her might and strength. Also he sayth, that when the Eagle ageth, the bill wareth so hard and so crooked, that unneth he may take his meate. And against this disadvantage he findeth a remedy. For he seeketh a stone, against the which he smiteth and beateth stronglye his bill, and cutteth of the charge of the bill, and receiveth meate and might and strength, and so becommeth young againe. And as Plinius saith, The Eagle sitteth on a rock or on a trée, & setteth the sight of her eyen against the cléernesse of the Sunne, or casteth her eien, & looketh hether and thether to espie her pray, or else beholdeth her owne clawes alway. Her gall is full medicinable: for when it is done in Colliriis, it sharpeth the sight, and helpeth against dimnesse, and other diseases of eien, as Dioscorides saith, & Constantine also. And hath some propertyes lesse worthy to be praysed, as is a Birde passing in heate and in drynesse: and therefore he is bolde and hardie and wrathfull: And for strong wrath is not but in bodies of great drinesse, as Arist[otle] sayth libro decimo sexto. The Eagle is enimy to innocent birds and foules, and pursueth them with her clawes, and taketh the Birde, and smiteth the head with her bill: and hath a lowing voyce, and generally fearing all other fowles. For in the sight and hering of the Eagle all foules of other kinde dreade, and also foules of pray. Therefore Plinius saith, That the gentle fawlcon or other such foules unneth take prayes on yt day, that they heare the Eagle. And that perchance commeth of great dreade. For generally all foules have dread of the Eagle, that taketh her pray onely in the aire, & they dread lesse ye Eagle that taketh her praye on the ground, & least of all that Eagle yt taketh her praye on the water. For no foules dread ye Eagle, but foules yt have their living and conversation in the water alonely. And such an Eagle goeth much out of kind & of noblenesse of those Eagles that take their pray in the aire, & on the earth, and that Eagle dreadeth the Vultur. Aristot[le] li. 15. saith, that such an Eagle Amachel dwelleth & abideth nigh the Sea, and fast beside greate lakes and ponds, and is fedde with birdes that bée nigh the sea. When they come out of the water, & happen to sée the Vulture comming, they will be afearde, and so they flye to the water, but the Vulture, that hath a right-sharpe sight, flyeth alwaye about that place: and if they flush out of the water into the ayre or into the land, the Vulture taketh them anone. And such an Eagle be long in the water, he is stifled. And ye Eagle hath one foote close and whole, as the foote of a Gander, and therwith she ruleth her selfe in the water, when she commeth down because of her praye. And her other foote is a clove foote, with full sharpe clawes, with the which she taketh hir pray [this story is usually told of the osprey]. And ye Eagles fethers have a privie fretting vertue, as Plinius saith. For he sayth, yt the Eagles feather done and set among feathers of wings of other Birds corumpteth and fretteth them. As strings made of wolves guttes done & put in a lute or in a harpe among strings made of shéepes guts, do destroy, and fret, and corrumpe the strings made of shéepes guttes, if it so be that they bée set among them, as in a lute or in a harp as he saith. Also the Eagle loveth not company: but voideth and flyeth companie, as Aristotle saith libro primo. It is not possible, that foules with crooked clawes shoulde abide with any of their fellowes. Also the Eagle hath claws in steed of sworde. And therfore when he sitteth on a stone he closeth in his clawes, and as it were hideth them within the fleshe, that hée hurt them not, neither smite them against the stone, as Aristotle saith, li. 13. A foule with crooked clawes bideth not long uppon trées, nor upon stones. For the kinde of their clawes is contrary to these two thinges. Also he is right cruell against her owne birds, when theyr eien be closed against the Sun: For then she supposeth that they be not her owne birds, when theyr eyen be closed against the Sunne. Also to teach and to compell them to take praye of other birdes, she beateth and woundeth them with hir bill, as Plinius saith.- [Batman]

Slavic Physiologus [15th - 16th century]: The eagle is the king of flying creatures. The eagle is good and lives without sorrow for one hundred years. When he gets old, he weakens and his eyes overflow and he cannot hunt. And he soars into the sky and drops onto a sharp stone, and the entire disease remains on the stone. Then he bathes in the paradise lake and stays in the sun for eight days. When he warms up from the sun, his eyes are cleared and he is rejuvenated. - [Stoykova, English translation by Mladenova and Stoykov]