[hackandthink]

"Mainstream metaphysics" means categorialism. Everybody knows about genus/species hierarchy.

"What is the relationship between categorialism and hylemorphism, Aristotle’s other major ontological theory? Where does matter fit, if at all, in the categorial scheme?"

https://plato.stanford.edu/entries/aristotle-categories/

[wduquette]

Hylemorphism is how Aristotle further subdivides the category of substance.