Excerpt from the poem: "Thy Godlike crime was to be kind,
To render with thy precepts less
The sum of human wretchedness,
And strengthen Man with his own mind;
But baffled as thou wert from high,
Still in thy patient energy,
In the endurance, and repulse
Of thine impenetrable Spirit,
Which Earth and Heaven could not convulse.."
If you read the poem you can tell he is telling him that by mixing in with the lives of mortals, he is only brought despair, because he lives forever while the do not and his attachments only end in pain and death.
Answer: Being too involved in the lives of mortal men.
