 As noted, Zhu drew on notions of qi, yin-yang, the five phases, shu (numbers, probablilities), and images as conceptual and categorical resources for classifying, characterizing, and understanding the world, especially cycles, processes, and particular things and events. Chinese thinkers, especially during the Han dynasty, used such notions to arrange categories of reality and compile lists of qualities for each category. While some of the associated qualities are directly or causally linked, many of them are arbitrary—perhaps assigned in light of long forgotten events or decrees. These sets of categories were compiled as systematic indices for grasping things and events in terms of categorical associations and imputations. Inevitably, these sets of categories bore a strongly cultural stamp and bias but were applied equally to natural phenomena, as if the natural world were an extension of the human world, not vice versa.