In Letter 16, Lady Susan makes some observations about love to Mrs. Johnson, specifically referencing her relationship to Mr. Manwaring. In the course of her observations, Lady Susan introduces an apt personification of her heart:
I infinitely prefer the tender and liberal spirit of Manwaring, which impressed with the deepest conviction of my merit, is satisfied that whatever I do must be right; and look with a degree of contempt on the inquisitive and doubting Fancies of that Heart which seems always debating on the reasonableness of its Emotions.
By personifying the heart, Lady Susan makes it into something self-aware and, in the true spirit of Enlightenment philosophy, capable of weighing emotion against reason. This passage reveals the more manipulative aspects of Lady Susan's personality, revealing that to her, love is a game of conquest, with winners and losers. In such a game, the heart becomes an active player in the world. As a partner, or, indeed, as an opposing player, Lady Susan here reveals that she far prefers someone who will love her unquestioningly: one who will not analyze his emotions, nor doubt the veracity of hers. In other words, she does not want an equal relationship, but one in which she has "won" through domination and beguilement.