 From this body of writings it may be inferred that Leontius was a monk, ascetic, and hermit.From the introduction of his third treatise "Against the Nestorians" we learn that as a young man, he was a member of the circle of Diodorus of Tarsus and Theodore of Mopsuestia.Leontius is best known for the theory of the "enhypostasia" (ἐνυποστασία) of the human nature of Christ in the divine hypostasis of the "Logos".