Long, long ago in lands far, far away, creatures of the AIR were held to be sacred. Athena's Owl,
Myths born of this epoch were said to be born of the Egg. It was metaphorically split in half (the duality of Gemini) with the upper half-Egg becoming the dome of Heaven, while the lower half-Egg took on a role as the Sea and Earth.
Birds became identified with the Will of the Divine as Heaven's Ambassadors. As late as the official state religions of the Greeks and Romans, birds are a mainstay of prophecy. The inauguration of Hellenic navigation each year opened and closed with the flight of pigeons just as the Pleiades once took flight in Spring.
Although the Vernal Equinox has long since moved out from under this Avian Influence, there's still one season during which these birds of a feather flock together. It's when we look up to behold the Summer Triangle.
The three most prominent stars of heaven through the summer are Deneb in Cygnus, Altair in Aquila, and Vega in Lyra.
Swan, Eagle... and Harp?
One of the more prominent constellations of the night sky because of both its brightness and position, Deneb marks the tail-feathers of the great Swan Cygnus. The early Greeks knew it as a Hen or Bird, while the Arabs of Sindbad day knew of it as the Roc.
Aquila has long been known as the Eagle. Early depictions showed this image carrying an arrow in its talons.
But a Harp?
Indeed. Early representations of the Harp show it hanging from the claws of an Eagle. From Star Names and their Meanings, p. 282.
"The association of Lyra's stars with a bird perhaps originated from a conception of the figure current for millenniums in ancient India- that of an Eagle or Vulture; and in Akkadia, of the great storm-bird Urakhga al Waki, Chilmead's Alvaka,- referring to the swooping Stone Eagle of the Desert, generally has been attributed to the configuration of the group alpha, epsilon, zeta, which shows the bird with half-closed wings, in contrast to Al Nasr al Tair, the Flying Eagle, our Aquila, whose smaller stars, beta and gamma, on either side of alpha, indicate the outspread wings."