"For most men in a brazen prison live,
Where in the sun's hot eye,
With heads bent o'er their toil, they languidly
Their lives to some unmeaning task-work give,
Dreaming of nought beyond their prison wall;
And as year after year
Fresh products of their barren labour fall
From their tired hands, and rest
Never yet comes more near,
Gloom settles slowly down over their breast,
And while they try to stem
The waves of mournful thought by which they are prest,
Death in their prison reaches them,
Unfreed, having seen nothing, still unblest."

By Augustine Birrell.
(Birrell is more of an essayist than a poet;
I found these few lines tucked into one of his essays.)