This hierarchy of immaterial entities contains nothing corresponding to our idea of personality. There is in it no principle that is both individual and immortal. Aristotle allows immortality only to the universal reason. The psychic elements are condemned to perish with the body. There is no hope for the parts of the soul which are most intimately connected with the individual's experience. Monophysite Christology shares this fundamental defect. The monophysite thinker attempted to express the union of two natures within one experience. But his psychology, not containing the notion of personality, could furnish no principle of synthesis. An agent in the background of life, to combine the multiplicity of experience, is a _sine qua non_ of a sound Christology. Personality was to the monophysites a _terra incognita_; and it was in large measure their devotion to Aristotle's system that made them deaf to the teaching of the catholic church. INTELLECTUALISM AND MYSTICISM COMPLEMENTARY SYSTEMS After this sketch of the Aristotelian features recognisable in monophysitism, we turn to the other great pagan philosophy that assisted in the shaping of the heresy. Intellectualism and mysticism are closely allied; the two are complementary; they are as mutually dependent as are head and heart. It is not then surprising that monophysitism should possess the characteristics of both these schools of thought. The intellectualism of the heresy was largely due, as we have shown, to the Aristotelian logic and metaphysic; its mystic elements derive, as we proceed to indicate, from Neo-Platonism and kindred theosophies.