Thoreau writes in his journal:
Cliffs.—Two little hawks have just come out to play, like butterflies rising one above the other in endless alternation far below me. They swoop from side to side in the broad basin of the tree-tops, with wider and wider surges, as if swung by an invisible pendulum. They stoop down on this side and scale up on that. Suddenly I look up and see a new bird, probably an eagle, quite above me, laboring with the wind not more than forty rods off. It was the largest bird of the falcon kind I ever saw. I was never so impressed by any flight.
