Now it pertaineth to speak of birds and fowls, and in particular and first of the eagle, which hath principality among fowls. Among all manner kinds of divers fowls, the eagle is the more liberal and free of heart. For the prey that she taketh, but it be for great hunger, she eateth not alone, but putteth it forth in common to fowls that follow her. But first she taketh her own portion and part. And therefore oft other fowls follow the eagle for hope and trust to have some part of her prey. But when the prey that is taken is not sufficient to herself, then as a king that taketh heed to a community, she taketh the bird that is next to her, and giveth it among the others, and serveth them therewith. Austin saith, and Plinius also, that in age the eagle hath darkness and dimness in eyen, and heaviness in wings. And against this disadvantage she is taught by kind to seek a well of springing water, and then she flieth up into the air as far as she may, till she be full hot by heat of the air, and by travail of flight, and so then by heat the pores are opened and the feathers chafed, and she falleth suddenly in to the well, and there the feathers are changed, and the dimness of her eyes is wiped away and purged, and she taketh again her might and strength. The eagle's feathers done and set among feathers of wings of other birds corrupteth and fretteth them. As strings made of wolf-gut done and put into a lute or in an harp among strings made of sheep-gut do destroy, and fret, and corrupt the strings made of sheep-gut, if it so be that they be set among them, as in a lute or in an harp, as Pliny saith. Among all fowls, in the eagle the virtue of sight is most mighty and strong. For in the eagle the spirit of sight is most temperate and most sharp in act and deed of seeing and beholding the sun in the roundness of its circle without blemishing of eyen. And the sharpness of her sight is not rebounded again with clearness of light of the sun, nother disperpled. There is one manner eagle that is full sharp of sight, and she taketh her own birds in her claws, and maketh them to look even on the sun, and that ere their wings be full grown, and except they look stiffly and steadfastly against the sun, she beateth them, and setteth them even tofore the sun. And if any eye of any of her birds watereth in looking on the sun she slayeth him, as though he went out of kind, or else driveth him out of the nest and despiseth him, and setteth not by him.