This is his definition of ontology. Where in Aristotles point of view, material objects are composed of matter (potential with no properties of its own) and form (its sensible qualities). Matter + sensible qualities=four elements. Example: hot: dry, hot: wet, cold: wet, cold: dry. The four elements; fire, air, water and earth. They go from lightest to heaviest. A thing can be described in terms of its four causes. Material cause, the matter making up an object, this is what persists through physical change. Formal cause, the objects sensible qualities, like shape, sixe, color. Agent or efficient cause, what creates or changes the objects, the source of its change.
Final cause, the purpose of the object or the goal of its change. Platos view on epistemology was very, unrealistic, in my point of view. He thinks that we know the material world imperfectly through our senses; we know the world of Forms truly through reason, because the eternal part of us remembers these forms. Our faculty of reason is superior to the senses, but the senses may also help direct our attention to the world of forms. Through Aristotles eyes, material objects are real, and empirical knowledge is true. We come to understand categories of things through our senses, through our experiences of real life examples.
In conclusion, Plato believed there is only one reality behind all of the phenomena in the world, the realm of the Ideal Forms. beieved that a world of Ideas or ideal forms existed apart from human beings. Aristotle, in contrast, argued there are a series of realities. At each level, the individual gets closer to the relationships that reveal true knowledge. Believed that no universals could exist apart from their relationship to human beings. In my point of view, Plato lived in a fantasyland. Where in Aristotle lived in a world that theres a scientific reason behind everything that happening.