Well, I feigned courtship of Miss Ingram, because I wished to render you as madly in love with me as I was with you; and I knew jealousy would be the best ally I could call in for the furtherance of that end.
Chapter 24 · Edward Rochester
Context
Rochester explains that his courtship of Blanche Ingram was a deliberate performance designed to make Jane jealous and thereby intensify her love for him.
Analysis
Rochester's metaphor of jealousy as an 'ally' he could 'call in' treats emotion as a strategic resource and Jane as an opponent in a campaign he was plotting to win. The verb 'feigned' applied to the entire courtship of Blanche exposes Rochester's comfort with elaborate deception in pursuit of his goals, while 'furtherance of that end' uses the bureaucratic language of means and ends, draining any spontaneity from what he still wants Jane to experience as romantic passion.
Essay Tip
Support a thesis that Rochester's confession reveals his love as fundamentally manipulative—he orchestrated Jane's suffering as a technique to 'render' her more attached, using courtship as psychological warfare and then expecting her to be flattered by the manipulation.