The micro monograph in the series Bielefeld Theory Talks is a new publication format created by the Center for Theories in Historical Research at the Department of History of Bielefeld University. The aim is to encourage theoretical debates in historical research by publishing ways of thinking that are both original and interdisciplinary. The core of each micro monograph is a detailed essay on key questions of historical theory originally given as a lecture – notably a Koselleck Lecture – at the Center for Theories. Each essay is accompanied by commentaries from a member of the Department of History at Bielefeld University and two international experts, who analyze the historical-theoretical position under review from their own scholarly perspective. Through these conversations, the series not only showcases a range of different theoretical positions, it also gives us an insight into the processes and practices of theorizing itself – a true theory in the making.