A man found a chicken's egg and put it in a nest of an eagle. The chick hatched with the brood of eaglets and grew up with them.
As he was growing up the chicken did what the eaglets did, thinking he was an eagle. He witnessed the others killing their siblings. He ate morsels of meat from his 'parents'. He stretched his wings and tried to fly.
Yet, try as he might, he could not fly as well as the eaglets.
He would thrash his wings and fly a few feet into the air, watching in frustration as the other eaglets glided in graceful majesty among the powerful wind currents, with scarcely a beat on their strong golden wings.
Frustrated, he thought to himself: "I can do anything I want. The only thing holding me back is my negative beliefs!"
So he launched himself off the eyrie and opened his wings... only to plummet down, dashing himself on the rocks far below.
As he lay dying, he saw a gawkish bird walking past him. It scratched the earth beside him for worms and insects, and then started to peck at the dying body of the chicken.
The mortally wounded chicken looked up in pain. "Who are you?" he asked. "I'm the chicken. I belong to the earth. And now I'm going to eat you, dying 'eagle'."
So the chicken lived and died an eagle, for that's what he thought he was.
For all of his short life, anyway.
Adapted from: On being an eagle by Anthony de Mello