In History in Times of Unprecedented Change: A Theory for the 21st Century, Zoltán Boldizsár Simon offers a groundbreaking examination of the historical sensibility centered on unprecedented change that has coalesced since the mid-twentieth century. Simon provides a compelling analysis of this new sensibility and deftly distinguishes it from the progressive philosophies of history that had reigned prior to its emergence. He also develops a crucial theoretical apparatus for registering the unprecedented in both historical ontology and historiographical theory. Chief here is his theory of “history as a disrupted singular,” which marks the unprecedented's disruption of any ontologically stable historical subject and reveals the future and the past to be not our own but the domains of different and alien subject formations. From this philosophical-historical foundation, Simon also provides a novel theorization of historical writing and historical experience that accounts for the overlapping registers of presence and absence that define our encounters with the past. Along with these innovations, Simon's book reorients former assumptions about historical change, historical subjectivity, and historical experience while revealing the extent to which the unprecedented-focused historical outlook dominates our relationship with the future. It also raises questions (directly and indirectly) about politics, continuity, and rupture that theorists of history must embrace.