Premodern philosophy originated in Antiquity, particularly in the writings of Plato and Aristotle. This introductory essay highlights points of cross-pollination between different schools, cultures, and moments in premodern thought, and prepares the ground for the rest of the volume by presenting different ways of approaching the Greek, Hebrew, Arabic, and Latin philosophical traditions. Some historiographies covering these traditions look forward, dynamically adapting, reworking, and molding what they find in their heritage to their own needs. Others look backward, seeking truth in stable origins. The approach proposed in this volume builds on a “source-based contextualism,” articulated most prominently by Richard C. Taylor, that assesses each medieval philosophical or theological text in light of other relevant philosophical and theological texts. We consider epistemic motifs that contextualize historical thinkers in their own spatial and temporal surroundings. Thus, there is a root from which different derivations arise, but each text is also contextually complex on its own account, and frames a philosophical problem in different ways within the living debates of particular times and particular spaces. The twenty-two chapters in the volume collectively apply this combined approach with different emphases, along the historiographical trajectories of “origins,” “developments,” and “innovations.”