The caged bird sings with a fearful trill, of things unknown, but longed for still, and his tune is heard on the distant hill, for the caged bird sings of freedom.
I have read in books that we are called 'caged birds'. I cannot speak for others, but I had so much in this cage of mine that there was not room for it in the universe- at least that is what I then felt.
Paleontologists have tried to turn Archaeopteryx into an earth-bound, feathered dinosaur. But it's not. It is a bird, a perching bird. And no amount of 'paleobabble' is going to change that.