The mortal realm has a second population, mostly invisible, and its census categories matter.
Jing (精) and guai (怪) — usually lumped together as yaoguai — are things that have woken up. The rule is simple and immense: anything that lives or lasts long enough, or absorbs enough essence of sun and moon, can become animate and intelligent. A fox of a hundred years becomes a fox-spirit. An ancient tree learns to speak. A rock, a lute, a mirror, a broom — given enough centuries and the right influences — may grow a soul. This is why the white peony in Pu Songling’s tale can love a scholar, and why the first question to ask of any marvel is: how old is it?
Their morality is not fixed. A spirit may be grateful (the snail-shell girl, repaying a kindness), predatory (the painted skin, wearing a human face as bait), mischievous, or simply strange — living its own life until a human blunders into it. What the genre insists on is that they are beings, not evil incarnate: most can be reasoned with, many can be loved, and nearly all are bound by rules that a clever human can learn.
Yishou (异兽), the strange beasts, are a different matter — not awakened objects but species: the fauna of the Shan Hai Jing, the Classic of Mountains and Seas. This is China’s bestiary, thousands of entries deep: the nine-tailed fox; the taotie, a glutton-mask that is all appetite; the qilin, a chimera of supreme gentleness that appears at the birth of sages; the baize, which knows the name and weakness of every spirit under heaven; birds with nine heads, fish that fly, oxen with a single leg. Unlike the sprites, these are simply there — native creatures of a stranger, larger world, catalogued by the old geographers with the sober tone of field notes.
Dragons (龙) deserve their own entry, but note the category difference: the dragon is neither sprite nor beast but water-god — a member of the divine administration with jurisdiction over rain, rivers and seas.
The general principle unifying all three categories is the one the whole universe runs on: seniority is power. Age, in this cosmos, is not decay but accumulation — of essence, of wisdom, of the ability to change shape and work wonders. The oldest things in the room are always the most dangerous, and the most interesting.