This chapter explains that unfelt affects are among the most subtly potent ones in eighteenth-century fiction, and they often decisively delineate character, advance plot, and confer a distinctive texture on narrative. The capacity of characters not to feel and not to notice feelings vitally supports the expressions of high emotion and intense desire long seen as among the novel's reasons for existence. In their privative sense, words like insensible and imperceptible sometimes serve as a plot device. Yet novelists also gesture to the insensible to evoke deeply meaningful affect, not merely as an alternative to the high-flown feelings evident in such fiction but also as a way of quietly enhancing their profundity. Moreover, these gestures help novelists navigate the perilous tensions and congruities between virtue and desire that are definitive of heroines' predicament in the marriage plot. The chapter then studies the insensible in the works of Henry Fielding, Samuel Richardson, Frances Burney, and Jane Austen.