It is interesting that for Zwingli, “spiritual” worship was synonymous with non-physical worship, while “purity” was equivalent with simplicity. Worship in Zwingli’s Zurich not only involved a ban on images, but also music, decoration and liturgical fragrance. In fact, during Zwingli’s first four years in the city, few themes featured as prominently as that of “invented external worship.” There was more at stake here than merely Zwingli’s concern to uphold the integrity of the Second Commandment: the root of his antipathy to material paraphernalia and external ceremony was that such practices were visible. For Zwingli the visible was the province of unbelief, while the invisible was the realm of faith. God, who is unseen, cannot be approached through the visible material of the created world, and it is a sign of spiritual immaturity for worshipers to be dependent on created things. Jealous to preserve God’s glory, Zwingli had sought to organize the relations between the spiritual and the material in a way that ensured the heavenly would never be mediated through the earthly. The more God could be seen to work independent of instrumentality, the greater God’s sovereignty was thought to be. Thus, in order for God to be fully magnified in all His transcendence, the spiritual potency of creation had to be either denied or heavily qualified; for God to have all the glory, creation must have none; to trust in God involved an inverse distrust in the elements of creation. His deep distrust of instrumental causality led Zwingli to seek to make the sacraments declarative rather than instrumental. He was, in the words of Gerrish, “reluctant to acknowledge any other causality than that of God, the first cause. Hence, the very notion of sacramental causality was offensive to him. It seems to detract from the immediacy of the divine activity if one assigns even an instrumental function to the creaturely elements of water, bread, and wine. Signs, for Zwingli, are not instrumental, but indicative or declarative.” Even Zwingli’s doctrine of predestination arose from this same impulse and was the inevitable correlate to saying that God was the only active cause operative among creatures. Significantly, when Zwingli had his iconic clash with Luther at Marburg, it was the former’s affirmation of the incompatibility of spirit and matter that led him to so forcefully oppose the doctrine of real presence.