Leontius of Byzantium whose identity is still debated, is the central figure of the sixth century. In his writing Adversus Nestorianos et Eutychianos he deepens the theology of Chalcedon on the person and nature: nature has reason to exist, has the significance of gender. It shows the feature of general reality. Hypostasis show self-existence itself. He discovers someone, “this one or that one”. Hypostasis looks different from common. Together with V and VI century theologians, Leontius is related to the teaching of the Cappadocian Fathers, which continues and deepens. As well as Cappadocian Fathers, Leontius defines person as a certain existence, which is bearing particular properties, which delimits the other existences defined. Nature shows the universal, hypostasis delineates the particular from common.