Although Charlotte Smith’s trademark emotional intensity has often been ascribed to her talent at channeling the discourses of sensibility and sympathy, this essay examines Smith as an arch-theorist of affect, or the fluctuations of matter in motion and at rest. The increasingly pervasive attention to the aqueous motion in several editions of Elegiac Sonnets reveals how affect crosses human and nonhuman boundaries through dynamic waves, winds, and voices working together. Dispersed yet fluid, this particulate materiality evinces a radically transposable, posthuman affect that circulates amid the human body and within nature. Smith’s elemental flow moves past discrete psychological and physiological emotion, subjects and bodies, into a more extensible affect that is materiality hospitable to nonhuman and even virtual worlds. The volume’s ever-changing, liquid contexture, finally, shapes the body of the poetic collection to be a continuously emergent field of affects, offering a wide array of materialities with all their potential to vary.