Analysis of After a Reading of “Darkwater”

I did not think... I did not know...
    What pale excuse is this I make
In answer to my brother’s woe,
Age-long, for deep injustice sake!

Across his mute and patient soul,
   While I have gone my heedless way,
The shadows of a fate might roll
   That deepened night and darkened day.

But I have read a burning page,
  That glowed with white and soul-wrung fire,
And now no more I may engage
    My conscience with a feeble hire.

For all the wrong I did not heed,
   Chance-born in happier paths to live,
I cry unto my brother’s need
  One word of love and shame... forgive!