The Matter of Beauty proposes that Victorian aesthetic theory is not a branch of philosophy focusing on art; rather, it is best understood as an interdisciplinary investigation of how humans relate affectively to physical things. The central claim of the dissertation is that aesthetic theory in the late-Victorian period enabled a significant reconsideration of what a "human" was, and of how distinctions could be drawn between self and other. I pursue this claim across four authors -- Walter Pater, William Morris, Grant Allen, and Vernon Lee -- who represent different modes in which a materialist strain of aesthetics led to a recognition that individuals constitutively lack autonomy from one another and from their surroundings.My analysis of a wide range of late-Victorian writing demonstrates that aesthetic theory responded to a question that was powerfully raised by nineteenth-century science, and that remains with us today: If our most elevated emotions can be localized as electrical activity in the brain, is there a "self" that transcends our material being? The intellectual tradition that I reconstruct reveals that considering aesthetic experience is a productive step toward answering this question. In their discussions of art and literature, Pater, Morris, Allen, and Lee develop a discourse of bodily sensations rather than of moral feelings; for them, aesthetic pleasure is important not because it is uplifting, but because it makes enjoyable the interconnectedness of bodies, minds, and matter. Furthermore, recovering this discourse allows us to revisit critical commonplaces about the political significance of Victorian aesthetics. Over the past two decades, the tendency has been to frame questions about the politics of aesthetics in oppositional terms: e.g., is aestheticism queer or misogynist, progressive or reactionary? I look elsewhere in order to evaluate the politics of aestheticism: representations of the individual as a material thing lacking autonomy reconfigured the relation between self and society. Materialist aesthetics showed individuals to be inherently dependent upon their contingent environments, thereby calling into question context-free ideals of personal freedom and individualism.