James Thomson - Once in a Saintly Passion

Once in a saintly passion
I cried with desperate grief,
"O Lord, my heart is black with guile,
Of sinners I am chief."
Then stooped my guardian angel
And whispered from behind,
"Vanity, my little man,
You're nothing of the kind."

James Thomson

http://www.poemhunter.com/poem/once-in-a-saintly-passion/