I’ll admit. This wasn’t my favorite. It’s not that I didn’t understand it, it’s just that its importance never “clicked” for me. But that’s more about me than the book.
“The science of substance must be of the nature of Wisdom” (996b).
The problem to be addressed: why are some things perishable and others are not if they consist of the same principles (Book III, 1000a)?
A substance is that which is not predicated of a stratum, but of which all else is predicated (Book VII: 3). The essence of each thing is that which is propter se.
- Compound of 1 and 2
A substance is that which is not predicable of a subject.
Back to the thesis: beings in the primary sense are substances; beings in the secondary sense are qualities et al. Yet we still haven’t answered the main question: what causes a thing to be a substance?