  Here personalists react not only to the main forms of idealism, the materialism, and the determinism of the nineteenth century, but even to the objectivism of Aristotle. Following his methodology for defining a species in terms of its proximate genus and specific difference, Aristotle had defined man as a rational animal (ho anthropos zoon noetikon) (Aristotle, Hist. Anim. I, 1: 488a7; Nichomachean Ethics I, 5: 1097b11; VIII, 12: 1162a16; IX, 9: 1169b18; Politics, I, 2: 1253a3). Personalists, while accepting this definition, as far as it goes, see such a construction as an unacceptable reduction of the human person to the objective world. This objective, cosmological view of man as an animal with the distinguishing feature of reason – by which man is primarily an object alongside other objects in the world to which he physically belongs – would be only partly valid, and insufficient. In an effort to interpret the subjectivity that is proper to the person, personalism expresses a belief in both the non-material dimension and the primordial uniqueness of the human being, and thus in the basic irreducibility of the human being to the natural world.