Soul For Plato, the soul is the invisible, rational life principle of a human being. Different kinds of people can be characterized by the relations among these parts, and an ideal arrangement can also be deduced. Intellect rules over Spirit, and these two together subdue Appetite. The Divided Line 1. Definitions Epistemology is the theory of knowledge.
Ontology is the theory of being.
The Divided Line Plato had a fairly well developed epistemology and ontology. In fact, his ontology and epistemology are intimately linked. In that realm is to be found the unchanging, ever-being, eternal forms, the things we love in the shadows around us. Matter, it follows, is a lesser stuff that is subdued and elevated by form. This results in a sharp form of dualism that looks down on things material and looks up to things spiritual and rational.