How does Anthony Trollope use imagery in Barchester Towers?

Imagery:

"'I don't want to save appearances; I want Mr. Slope to appear just what he is - a false, designing, mean, intriguing man. I have my eye on him; he knows little what I see...If he doesn't look well to it, he'll have his gown stripped off his back instead of having a dean's hat on his head. Dean, indeed! The man has gone made with arrogance."'