This preface argues that modern scientific theories of the earth emerged on the slopes of Javanese volcanoes since the late nineteenth century. The theory of plate tectonics was forged in part by scientists coming to understand the relationship between the ocean and volcanism in Java. Those who believe in the theory of plate tectonics, in fact, inherit the spiritual geographies of Indonesian volcanism. Theories of the Anthropocene are prefigured by much older debates about Javanese volcanoes and about the relationship between society and geological matter. The modern geological sciences separated society from volcanic processes; the Anthropocene is their return. Reconsidering these debates can offer strategies for how to live in a world of increasingly uncertain natural systems and volatile geology. The division between geos and bios has long been porous in Javanese geological thought. Theology, cosmology, and volcanology have been crucially bound together in Indonesia.