 The crux of the idea is to examine extended periods of time and draw conclusions from historical trends and patterns.The "longue durée" is part of a tripartite system that includes short-term "événements" and medium-term conjunctures (periods of decades or centuries when more profound cultural changes such as the industrial revolution can take place).The approach, which incorporates social scientific methods such as the recently evolved field of economic history into general history, was pioneered by Marc Bloch and Lucien Febvre in the Interwar period.