From Lucretius to the twelfth century, this book traces the formative history of one of Western philosophy's most enduring concepts: prime matter. It examines how ancient, late antique, and early medieval thinkers interpreted corporeal reality, reshaping the relationship between matter, form, and change. By reconstructing this early phase, the book reveals the conceptual tensions and creative syntheses that defined Latin debates on the ontology of matter before the full reception of Aristotle, including discussions of Islamic and Jewish philosophical traditions. This period emerges as a laboratory of metaphysical experimentation, in which questions about potentiality, substrate, and divine causality reconfigured debates in metaphysics, natural philosophy, and theology. Written by leading scholars in the field, A Philosophical History of Prime Matter. Volume I: Ancient and Pre-Scholastic Conceptions offers a systematic account of the origins and early transformations of hylomorphism in the Latin tradition.