of Aristotle's assertions concerning principles of being. For God as prima causa ("first cause") comes from Aristotle's concept of the unmoved mover and asserts that God is the ultimate cause of all things. Nature of Jesus Christ In the Summa Theologica Thomas begins his discussion of Jesus Christ by recounting the biblical story of Adam and Eve and by describing the negative effects of original sin. The purpose of Christ's Incarnation was to restore human nature by removing the contamination of sin, which humans cannot do by themselves. "Divine Wisdom judged it fitting that God should become man, so that thus one and the same person would be able both to restore man and to offer satisfaction." Thomas argued in favor of the satisfaction view of atonement; that is, that Jesus Christ died "to satisfy for the whole human race, which was sentenced to die on account of sin." Thomas argued against several specific contemporary and historical theologians who held differing views about Christ. In response to Photinus, Thomas stated that Jesus was truly divine and not simply a human being. Against Nestorius, who suggested that Son of God was merely conjoined to the man Christ, Thomas argued that the fullness of God was an integral part of Christ's existence. However, countering Apollinaris' views, Thomas held that Christ had a truly human (rational) soul, as well. This produced a duality of natures in Christ. Thomas argued against Eutyches that this duality persisted after the Incarnation. Thomas stated that these two natures existed simultaneously yet distinguishably in one real human body, unlike the teachings of Manichaeus and Valentinus. With respect to Paul's assertion that Christ, "though he was in the form of God... emptied himself" (Philippians 2:6–7) in becoming human, Thomas offered an articulation of divine kenosis that has informed much subsequent Catholic Christology. Following the Council of Nicaea, Augustine of Hippo, as well as the assertions of Scripture, Thomas held the doctrine of divine immutability. Hence, in becoming human, there could be no change in the divine person of Christ. For Thomas, "the mystery of Incarnation was not completed through God being changed in any way from the state in which He had been from eternity, but through His having united Himself to the creature in a new way, or rather through having united it to Himself." Similarly, Thomas explained that Christ "emptied Himself, not by putting off His divine