 The model that dominated modern European thinking about causality—linear causality through collision (on the model of billiard balls)—was not central to Chinese reflections on causality (as it was not central in Europe before the late Renaissance). For Chinese philosophers, the paradigms for causality were things like the effects of music over a distance, the relationship between spring and the growth of plants, and the influence between a teacher and student. This orientation followed from belief that all things are interconnected and are ultimately composed of the same stuff, qi. It also reflected practical concerns—How does culture work so that people can live together harmoniously? How do we relate to nature in a way that is sustainable? Approaching causality from this direction, though, is notoriously difficult. Han dynasty philosophers were basically starting from what we might now call ecological thinking or theories of complexity.