In this introduction, we explain our choice to approach the topic of space from a cosmological perspective, that is, by studying the conceptions of space that were implicitly or explicitly entailed by ancient, medieval and early modern representations of the cosmos, and the role that imagination played in those conceptions. We compare our approach with those of Alexandre Koyré and Edward Grant, and we present the two important issues this book intends to shed light on, namely the continuity and discontinuity between ancient, medieval, and early modern conceptions of space and the cosmos; and the role that metaphysical, cosmological, and theological considerations played in the elaboration of new theories of space in the course of history. This chapter also presents the main, recurring themes of this book: the relation between place and space; the notion of imaginary spaces; the role played by thought experiments in discussions concerning the nature of space and the structure of the cosmos; the impact of the condemnation of 1277 on subsequent theories of space; and the relation between God's immensity and the infinity of space.