Isn't that just a function of how you choose to perceive? For example, the water in a river, and our skin cells are constantly replacing themselves, even thoug

Isn't that just a function of how you choose to perceive? For example, the water in a river, and our skin cells are constantly replacing themselves, even though it might not seem that way--what I mean is, maybe one's epithelium is more like an immutable structure, each time displacing the one that came before. Or consider atoms, which sort of have immutability as a core concept.