Watch the second part of this lecture, from 34:00 to the end, and focus on understanding the competing analytical models historians have used to explain revolutionary change. O'Brien discusses several models which make connections between revolutions and the following factors: Marxist theory, political centralization, modernization, intellectuals, and the international context. As you listen to the lecture, make sure you can discuss each of these, and identify the most important theorist associated with each approach. More broadly, consider the following questions: what are the advantages of building conceptual models to characterize revolutions? What are the drawbacks of using conceptual models to understand history?