On flight

Birds that I thought so free With all of up and down to be Their own flit; Back and forth, South and North, the whole of it. No roads to cut the sky But what are charted by Swift chop of wing, I watched you, envying Your shadows there -- Free, free as air! But they tell me Now, air's not free; It has its boundary. Prisoned in one small square Where is the bird that dare Move out of his own sphere? Then, if all cells we find Built first within the mind, Birds, let us here Cunningly engineer An opening chink, a crack; defy These crumbling walls, and head for sky.