A little further explanation:
“When the bread is eaten outwardly, there is a ‘at the same time’ an inward feeding on Christ’s body. God is offering that which is signified by the elements, just as in the preaching the offer of the gospel is given. This view is found in Bullinger’s Second Helvetic Confession (1566; see BC 5.183; 5.203). This emphasizes the ‘present tense’ – indicating what is happening as believers participate in the Lord’s Supper. Gerrish notes: ‘This, of course, does take us beyond Zwingli, whose characteristic tense is the past, not the present. In Zwingli’s view, the elements call to mind something that has happened: Christ’s body was broken, we have turned to him in faith. And yet Bullinger’s parallelism is not Calvin’s position either, for it lacks the use of instrumental expressions; the outward event does not convey or cause or give rise to the inward event, but merely indicates that it is going on.’ See Gerrish, ‘Sign and Reality,’ 124. Gerrish notes that ‘where Calvin and Bullinger never agreed was over Calvin’s belief that God performs the inward through the outward,’ Grace and Gratitude, 167 n.29. For Calvin, God in sacraments ‘does not feed our eyes with a mere appearance only, but leads us to the present reality and effectively performs what it symbolizes.’ See Inst. IV.15.14 and IV.17.3.”
Introducing the Reformed Faith: Biblical Revelation, Christian Tradition By Donald K. McKim
A post I made a while back on the same subject here.