In 1527 Dr. Martin Luther wrote his first major treatise on the Lord’s Supper: That These Words of Christ, “This Is My Body,” Etc., Still Stand Firm Against the Fanatics. In this work he sought to refute the Eucharistic teachings of Ulrich Zwingli, Johannes 
Oecolampadius, and a few others whom he called “fanatics” or “sacramentarians.” One section deals with Oecolampadius’ references to the statements of certain early Church Fathers in support of his symbolic understanding of the Lord’s Supper. Oecolampadius (originally Hausschein) came from southwestern Germany and had become a reform-minded preacher in Basel, Switzerland. Dr. Luther particularly wanted to defend the reputation of Augustine of Hippo against Oecolampadius’ false interpretation of the Church Father’s teaching on the Lord’s Supper:
“Holy Christendom has, in my judgment, no better teacher after the apostles than St. Augustine. Should this dear and holy teacher be so reviled and defamed by the fanatics as to be regarded as the cloak and support of their poisonous, deceptive teaching? To this I shall answer No as long as I have breath; this does him an injustice. Indeed, it is a good thing to say No to this, because the fanatics interpret his words only according to their own understanding, and yet do not prove their interpretations; still they boast that they have the clear, pure truth with certainty. Their proof amounts only to this: It could be so understood.” [Martin Luther, “That These Words of Christ, ‘This is My Body,’ Etc., Still Stand Firm Against the Fanatics,” Luther’s Works, vol. 37, p. 107.]
Luther asserted that Oecolampadius misunderstood Augustine and other early Church theologians regarding the Lord’s Supper. For instance, Luther wrote,
“To be sure, they regard St. Augustine as their own, for he often uses the words mystery, sacrament, sign, invisible, intelligible. But Oecolampadius can deduce nothing from this, despite his boast that he has the definite truth. For although St. Augustine often says that the bread in the Supper is a sacrament and sign of the body of Christ, Oecolampadius has not yet established thereby that mere bread and not Christ’s body is present, because one can say that Christ’s body is invisibly present under a visible sign….St. Augustine does not say that a sacrament is a figure or sign of something future or absent, like the stories of the Old Testament, but a form of something present and yet invisible.” Ibid., p. 104.