Analysis of A Caged Mocking-Bird

I pass a cobbler's shop along the street
And pause a moment at the door-step, where,
In nature's medley, piping cool and sweet,
The songs that thrill the swamps when spring is near,
Fly o'er the fields at fullness of the year,
And twitter where the autumn hedges run,
Join all the months of music into one.

I shut my eyes:    the shy wood-thrush is there,
And all the leaves hang still to catch his spell;
Wrens cheep among the bushes; from somewhere
A bluebird's tweedle passes o'er the fell;
From rustling corn bob-white his name doth tell;
And when the oriole sets his full heart free
Barefooted boyhood comes again to me.

The vision-bringer hangs upon a nail
Before a dusty window, looking dim
On marts where trade goes hot with box and bale;
The sad-eyed passers have no time for him.
His captor sits, with beaded face and grim,
Plying a listless awl, as in a dream
Of pastures winding by a shady stream.

Gray bird, what spirit bides with thee unseen?
For now, when every songster finds his love
And makes his nest where woods are deep and green,
Free as the winds, thy song should mock the dove.
If I were thou, my grief in moans should move
At thinking--otherwhere, by others' art
Charmed and forgetful--of mine own sweetheart.

But I, who weep when fortune seems unkind
To prison me within a space of walls,
When far-off grottoes hold my loves enshrined
And every love is cruel when it calls;
Who sulk for hills and fern-fledged waterfalls,--
I blush to offer sorrow unto thee,
Master of fate, scorner of destiny!