Isaiah 40:31
...but those who hope in the Lord will renew their strength. They will soar on wings like eagles; they will run and not grow weary, they will walk and not be faint.

The eagle represents freedom. Living as he does on the tops of lofty mountains, amid the solitary grandeur of Nature, he has unlimited freedom, whether with strong pinions he sweeps into the valleys below, or upward into the boundless spaces beyond.
It is said the eagle was used as a national emblem because, at one of the first battles of the Revolution (which occurred early in the morning) the noise of the struggle awoke the sleeping eagles on the heights and they flew from their nests and circled about over the heads of the fighting men, all the while giving vent to their raucous cries. "They are shrieking for Freedom," said the patriots.
Thus the eagle, full of the boundless spirit of freedom, living above the valleys, strong and powerful in his might, has become the national emblem of a country that offers freedom in word and thought and an opportunity for a full and free expansion into the boundless space of the future. --Maude M. Grant