When an eagle is old, its eyesight dims and its feathers and wings become heavy. To rejuvenate itself, the eagle flies up to the region of the sun, which burns away the mist over its eyes and burns off its old feathers. The eagle then plunges three times into water, and its youth is restored. Also as a result of age, the eagle's beak grows until the bird can no longer eat; by striking its beak against a rock, the eagle breaks its beak which then grows back.

The eagle's eyes are very sharp and can see fish when the bird flies over water. The eagle can look directly into the sun. As a test of the worthiness of its young, the eagle holds them up facing the sun. The birds that cannot stare into the sun and turn their eyes away are cast out of the nest. Some authors say that the eagle's rejected chicks are adopted by the coot or the vulture.

The eagle received both favorable and unfavorable interpretations.

As the eagle renews its youth, so too can the man with "old clothes and dim eyes", who should seek the spiritual spring and raise the eyes of his mind to God. The rock on which the eagle sharpens its beak is Christ, on which man can sharpen his soul; the eagle also represents Christ, who came from heaven to catch souls, just as the eagle catches fish. The eagle's ability to look directly at the sun represents Christ's ability to look directly at God, and as the eagle lifts its young to the sun, so do angels lift worthy souls to God.

According to the Aberdeen Bestiary, "The word 'eagle' in the Holy Scriptures signifies sometimes evil spirits, ravishers of souls; sometimes the rulers of this world. Sometimes, in contrast, it signifies either the acute understanding of the saints, or the Lord incarnate flying swiftly over the depths then seeking once more the heights. The word 'eagle' represents those who lie in ambush for the spirit. ... The word 'eagle' also symbolizes earthly power." The descent of the eagle from the sky to the earth to find food also represents the fall of Adam, who ate what was forbidden.

The various attributes of the eagle are illustrated in several ways. A common illustration is a composite view where the eagle flies up to the sun to burn the mist from its eyes and then dives into a pool of water. Simplified forms only show the eagle staring into the sun (Koninklijke Bibliotheek, KB, 76 E 4, folio 37r) or in the water (Bibliothèque Nationale de France, fr. 14964, folio 129v) or diving into the water (Bibliothèque de l'Arsenal, Ms-3516, folio 202v).

To this is sometimes added an eagle carrying a fish to feed its young (for example, Aberdeen University Library, Univ. Lib. MS 24, folio 61v and Bodleian Library, MS. Bodley 764, folio 57v).

In many illustrations the eagle is just presented in profile, not doing much of anything. In a few images the eagle is wearing a crown to show it is the king of the birds (Houghton Library, MS Typ 101, folio 14r; Universiteitsbibliotheek Leiden, BPL 14 A, folio 58v).

The requirement that eagle chicks be able to stare into the sun or be rejected is graphically illustrated in British Library, Royal MS 12 F XIII (folio 49r) and Bibliothèque Municipale de Chalon-sur-Saône, MS 14 (folio 73v), where a chick that failed the test is thrown out of the nest.

The gall of an eagle mixed with honey and rubbed on a person's eyes will restore vision and give the person very acute sight.

If you put an eagle's beak to your head at night, you will be able to dream anything you want.

Magical stones are associated with the eagle. There is a stone called midriosi that eagles use to restore their sight; this stone will also restore sight in humans if worn as a ring. Eagles keep a stone called ethitem or jet in their nests to protect the eggs from excessive heat; this stone is useful for many remedies. Above the eagle's eyes are two stones which are a powerful deterrent against demons.