What is the one big idea of Koselleck’s Historik understood as a methodological framework for the attempt to combine a theory of historical times with a theory of historical time? In part (1) of this paper, I criticize the two most basic attempts to understand Koselleck’s one big idea as mistaken because they are exclusively interested either in history (in the singular) or in histories (in the plural) and thus miss the central relevance of structures of repetition (“Wiederholungsstrukturen”) for Koselleck’s Historik. In part (2), I will clarify the rather hidden pre-history, the main ambition, the theoretical context and the substantial content of Koselleck’s concept of structures of repetition in history and language. In part (3), I will discuss four historiographical consequences of Koselleck’s structures of repetition. I will end the paper by observing a remarkable theoretical affinity between Barrington Moore’s search for recurring patterns in the field of sociology and Koselleck’s structures of repetition in history and language. Moore’s work illustrates the historiographical potential of the one big idea of Koselleck’s Historik better than any other work I am aware of.