ABSTRACT
Aristotle outlines his project in the Metaphysics as the investigation of the knowledge of existence, in a section that sets down the limits of metaphysics and can also be taken as definitive of ontology. There is a branch of knowledge that studies being qua being, and the attributes that belong to it in virtue of its own nature. Both Karl Marx and Aristotle work on the basis of an ontology of universalia in rebus rather than on the Platonic schema of universalia ante rem. Aristotle offers a de-reified account of soul and resolves what others take to be some kind of thing into a set of powers, or capacities whilst simultaneously remaining on the terrain of ontology, talking of what exists though not of what things exist. Consideration of relationship between matter and form composite substances introduces an important problem in Aristotelian metaphysical interpretation, which M. L. Gill in her work Aristotle on Substance has called the paradox of unity.
