Analysis of A Relapse

I thought that I had done with fleshly things,
That in the azure of high thought my soul
Had learned to fly on less substantial wings
To a new Heaven, a sublimer goal.
I thought that I was wise beneath the cowl
Of my dead hopes, beyond all power of Spring's
Most eloquent music to again cajole,
And that my service was the King of Kings.
--But look, alas, how thoughtless thought can be,
For to me thinking thus one ventured in
Bearing a letter and I read your name.
Then in an instant through my limbs a flame
Of pleasure ran, and wrought such change in me
That I was eager for all loveliest sin.