Simmel writes in his essay "The Change of Cultural Forms" from 1916: "Between the ever-increasing, ever-expanding life with its ever-greater energy and the forms of its historical expression, which remain in rigid equality, there inevitably exists a conflict that fills the entire history of culture, although it naturally remains latent in places. However, in the present, it seems to me to be in full swing for a large number of cultural forms." This fundamental idea is elaborated in Simmel's essays and treatises between 1909 and 1918 in its various facets. They encompass philosophical studies of art, metaphysical and epistemological inquiries, "brilliant portraits of ideas" (Der Spiegel) about artists like Rembrandt and Goethe, as well as works on the World War and its significance for European culture, in which life philosophy and contemporary diagnosis are intertwined.