The hawk or falcon was, above all, the sacred bird of ancient Egypt, embodied in Horus, the sky-god and divine model of kingship, shown as a falcon or a falcon-headed man whose eyes were the sun and the moon; the living pharaoh was Horus on earth. The sun-god himself was worshipped in falcon form as Ra-Horakhty, Horus of the two horizons, a falcon-headed figure crowned with the solar disc. The bird's soaring flight and its keen far-seeing eye made it a natural image of the sky, the sun and the all-seeing divine, and the human-headed hawk could depict the ba, an aspect of the soul.
The hawk's real physiology backs up its old reputation for unmatched sight: a hawk's eye is estimated to resolve detail some two to three times more sharply than a human eye, with a density of light-sensing cells in the retina far beyond ours and, in many species, a second area of sharp focus angled to the side of the head as well as forward, letting the bird track prey below while still watching the wider sky, a genuine optical basis for the far-seeing eye the Egyptians read as the sun and the moon. Egyptologists disagree on exactly which bird stood behind Horus's falcon form, since ancient art is rarely precise enough to distinguish species; the lanner falcon and the peregrine falcon are the two most commonly proposed candidates, both native to the Nile valley and both fast, keen-eyed hunters, and the identification remains a matter of informed inference rather than settled fact.