The first line I kept mostly intact from Wordsworth's famous poem, "A slumber did my spirit seal," which basically refers to how the poet's spirit was ignorant and in a "slumber," deluded and unaware of the true way things are. UNKewlJ was (is) deluded, in a "slumber," about the effectiveness of his lying.
They seemed a thing that could not feel, refers to the forum readers, YES, that he thought that we couldn't feel his lies, that he was getting over on us, or hoping that he had gotten over on us. That line too is more or less intact from the original poem.