In the philosophical area of metaphysics there is a subfield called ontology, which focuses on figuring out how to define & distinguish between kinds of being. According to reading 8 ( introduction to metaphysics) , there is a major division between material & immaterial things . Give an easy/obvious example for both categories. Now , find something hard to categorize & explain why you think it’s difficult.
Now, recall that some theories of reality consider certain kinds of beings more fundamentally real than other kinds of beings. Looking at three examples you just gave; which being would Epicurus consider more real than the others & why ?