This chapter examines a core hypothesis of the intellectual historian Reinhart Koselleck: that modern political concepts underwent an accelerated period of change during the latter half of the eigheenth and the first half of the nineteenth centuries, a period he calls the ‘Sattelzeit’ or hinge period of intellectual history. Adapting word embedding models and metrics of novelty and the pace of change, this chapter helps to measure, visualise and disentangle the precise semantic transformations occuring at this threshold period: the consolidation of Koselleck’s ‘collective singular’ noun, for example, appears alongside a host of other cultural, technological, intellectual innovations in word usage. Finally, the data reveal not one but two revolutionary semantic periods between 1720 and 1960, a finding which both troubles the concept of a Sattelzeit while also extending it into new discursive, historical – and digital – contexts.