Full Idea
Aristotle's mature ontology takes biological organisms as its paradigm substances.
Gist of Idea
Mature Aristotle sees organisms as the paradigm substances
Source
report of Aristotle (Metaphysics [c.324 BCE]) by Robert Pasnau - Metaphysical Themes 1274-1671 26.1
Book Reference
Pasnau,Robert: 'Metaphysical Themes 1274-1671' [OUP 2011], p.610
A Reaction
'Mature' is here to eliminate 'Categories' where, I take it, any coherent object counts as a substance, with the categories giving the essence. Organism are more clearly categorised, but that's all. Van Inwagen makes this idea a key one.