Individual Substance of Rational Nature: The Personification Principle and the Nature of the Separated Soul

Abstract

The person, according to Boecio and Thomas Aquinas, is an individual substance of rational nature, that is to say, a suppositum and, as such, it is something complete, an unitary whole whose fundamental aspects are individuality and subsistence. Accordingly, the mind is what defines suppositum as a person, and it is also what essentially differentiates it from inanimate individuals, animals and plants. However, his formal constituent is the esse, the act of being a person. From esse, the subsistence of the person is revealed as self-possession and individuality as total incommunicability, both of them belonging to a full being. In addition, the separated soul is not hypostasis in the sense that it is part of a species as incomplete substance, but its esse that becomes the person and belongs to it. In this sense, it retains its personal nature, and it explains its natural tend to reunite with the body