Hannah Arendt became famous for her works "The Origins of Totalitarianism", "The Human Condition", and "Eichmann in Jerusalem". Yet her scholarly career began with an exploration of Saint Augustine's concept of caritas, or neighbourly love. Although she commissioned an English translation of her 1929 dissertation, written under the direction of Karl Jaspers and the influence of Martin Heidegger, and annotated and revised it extensively in the late 1950s and early 1960s, the English manuscript was never published. This study is a revised English translation of the work that incorporates Arendt's own substantial revisions of the original text and provides additional notes based on letters, contracts, and other documents as well as the recollections of Arendt's friends and colleagues during her later years. In an interpretive essay, the editors trace Arendt's characteristic mode of discourse to this dissertation, as she introduced concepts that came to resonate throughout her work: caritas, plurality, natality, memory, free will, and love of the world. They argue that the entire revised text is not only a study of neighbourly love and worldliness in relation to the possibility of free will, but also a phenomenological discussion of the social and moral origins of action in the public realm. Scott and Stark demonstrate how Arendt's early work on Augustine provides the key to her later critique of modernity. Her main works are filled with explicit and implicit Augustinian references: the question about the relevance of the neighbour; her conclusion that Augustinian philosophy is both out of, and engaged in, the world; and the path she followed to reach them, combining phenomenology with Christian existentialism, were essentially unchanged even in the context of New York in the early 1960s.