In the past two decades, several landmark works of intellectual history have attempted to chart the development of “secular modernity”, generally locating its origins in medieval or Protestant metaphysical assumptions. These works are genealogies, constructive projects within which historical narrative functions to uncover truths about social phenomena that would otherwise remain hidden. Several key claims of these genealogies, however, fail to withstand scrutiny: they operate with a model of intellectual change that assumes it results from the success of certain new ideas and locate the origins of secularity too early. If historians wish to better understand development of secularity, a more helpful entry point is a seventeenth-century debate about the immateriality of the soul, the nature of space, and the spirit of God. Understanding how Cambridge Platonist Henry More, among the most prominent philosophers in Europe during his lifetime, attempted to defend certain traditional metaphysical commitments simultaneously illuminates that intellectual change results as much from the failure of ideas as their success and reveals the origin of a key idea identified with secular modernity in recent genealogies.