Concentrating on six plays in the 1610s, this thesis explores the ways theatrical visual effects described as “strange” channel the period’s moral anxieties about rhetoric, technology, and scepticism. It contributes to debates in repertory studies, textual and material culture, intellectual history, theatre history, and to recent revisionist considerations of spectacle. I argue that “strange” spectacle has its roots in the materialisation of morality: the presentation of moral ideas not as abstract concepts but in physical things. The first part of my PhD is a detailed study of early modern moral philosophy, scepticism, and material and textual culture. The second part of my thesis concentrates on Shakespeare’s Cymbeline (1609-10) and The Tempest (1611), John Webster’s The White Devil (1612), and Thomas Heywood’s first three Age plays (1611-13). These spectacular plays are all written and performed within the years 1610-13, a period in which the changes, challenges, and developments in both stage technology and moral philosophy are at their peak. I set these plays in the context of the wider historical moment, showing that the idiosyncrasy of their “strange” stagecraft reflects the period’s interest in materialisation and its attendant moral anxieties. This thesis implicitly challenges some of the conclusions of repertory studies, which sometimes threatens to hierarchise early modern theatre companies by seeing repertories as indications of audience taste and making too strong a divide between, say, “elite” indoor and “citizen” outdoor playhouses. It is also aligned with recent revisionist considerations of spectacle, and I elide divisions in criticism between interest in original performance conditions, close textual analysis, or historical-contextual readings. I present “strangeness” as a model for appreciating the distinct aesthetic of these plays, by reading them as part of their cultural milieu and the material conditions of their original performance.