This paper elaborates upon various responses to the Problem of the One over the Many, in the service of two central goals. The first is to situate Huayan's mereology within the context of Buddhism's historical development, showing its continuity with a broader tradition of philosophizing about part-whole relations. The second goal is to highlight the way in which Huayan's mereology combines the virtues of the Nyāya-Vaisheshika and Indian Buddhist solutions to the Problem of the One over the Many while avoiding (...) their vices. (shrink)