The first major work in the history of philosophy to bear the title “Metaphysics” was the treatise by Aristotle that we have come to know by that name. But Aristotle himself did not use that title or even describe his field of study as ‘metaphysics’; the name was evidently coined by the first century C.E. editor who assembled the treatise we know as Aristotle’s "Metaphysics" out of various smaller selections of Aristotle’s works. The title ‘metaphysics’—literally, ‘after the Physics’—very likely indicated the place the topics discussed therein were intended to occupy in the philosophical curriculum. They were to be studied after the treatises dealing with nature (ta phusika).
Plato, in his theory of forms, separates the sensible world (appearances) of the intelligible world (ideas) and the intelligible world was the only reality, the foundation of all truth. But in Aristotle’s "Metaphysics", at the heart of his philosophy, such separation removes any intelligibility and meaning to the world. According to him, the intelligibility is present in every being and in every thing. The world consists of substances. The substance can be either matter or form, or a compound of both. The shape is that, in every being, is general, so intelligible. For example the shape of a dog is what is common to all dogs. The matter is what is special, so unknowable.
There would be a hierarchy of beings, matter informally unknowable to the pure form perfectly intelligible (God). This hierarchy justifies what Aristotle calls slavery by nature...