  Though the philosophical concept of person first developed in this theological context, with reference to the persons of the Trinity, the general Greek philosophical concepts involved in these Trinitological origins facilitated its application to human beings as well. Philosophical personalism may or may not appropriate the theological suppositions with which the early usage of the term “person” is laden. The classic, basic, and purely philosophical definition which is still accepted by personalists, as far as it goes, was given early on by Boethius (ca. 480–524): “persona est naturae rationalis individua substantia.” This definition consists of two parts. The essential starting point is a subsistent individual: a singular, existing suppositum or ύπόστασις. Here the adjective “individual” distinguishes an existing substance from common or second substance. The second element of the definition – naturae rationalis – qualifies the notion of individual substance: the person is an individual possessing a rational nature. It is this rational, spiritual nature that gives rise to the different qualities that distinguish the person, qualities to which personalists attach decisive importance.