More than twenty years, years which include the First World War as well as the rise of National Socialism, separate Husserl's last great work, The Crisis of European Sciences and Transcendental Phenomenology from the main text of Ideas II. Between the two lies the work of the 1920s, including the development of genetic phenomenology along with the method of Abbau and Aufbau, and the investigations of the living present of the early 1930s (now deposited in the "C' manuscripts). However, the most important difference between the two works can be summed up in one word: "Lebenswelt."