I know why the caged bird sings, ah me,
When his wing is bruised and his bosom sore,—
When he beats his bars and he would be free;
It is not a carol of joy or glee,
But a prayer that he sends from his heart’s deep core,
But a plea, that upward to Heaven he flings—
I know why the caged bird sings! 

– Paul Laurence Dunbar

There is still slavery in the world. There is still a valuing of human beings according to their race or class or gender or culture or sexuality. Part of the reason for this cutting off of empathy is the anesthetizing of our senses to the suffering of animals. Once we grow callous, we cannot feel fully for anyone- not even for ourselves.

Gloria Steinem

I too many and many a time cross’d the river of old,
Watched the Twelfth-month sea-gulls, saw them high in the air floating with motionless wings, oscillating their bodies,
Saw how the glistening yellow lit up parts of their bodies and left the rest in strong shadow,
Saw the slow-wheeling circles and the gradual edging toward the south
– Walt Whitman, Crossing Brooklyn Ferry