During the first phase of the Iconoclastic Controversy (717–787), John of Damascus emerged as the chief spokesman of the iconodules. His apologetic for icons, developed in his Treatises Against Those Who Attack the Holy Images (around 730) provided the rationale for the dogmatic decree legitimizing icons, which was adopted at the Seventh Ecumenical Council (Nicea II, 787). Exegetical, hermeneutical, and christological arguments played the dominant roles in his defense of the legitimacy of icons. An additional element in the Damascene's apologetic was an innovative theory of human cognition which placed a high value on created materiality, and thus extended the traditional Eastern Christian appreciation of the material world.