Unfortunately this union of minds, that was now to be sought after above all things, was a very difficult task. Luther in 1519 had at first appeared not only to reform, but entirely renovate the doctrine of the Lord's Supper, as the Swiss did somewhat later. "I go to the sacrament of the Lord's Supper," he had said, "and I there receive a sign from God that Christ's righteousness and passion justify me; such is the use of the Sacrament."[188] This discourse, which had gone through several impressions in the cities of Upper Germany, had prepared men's minds for the doctrine of Zwingle. Accordingly Luther, astonished at the reputation he had gained, published this solemn declaration in 1527: "I protest before God and before the whole world that I have never walked with the Sacramentarians." [188] In the writing entitled, _Dass diese Worte noch feste Stehen_.--(L. Opp. xix.) [Sidenote: A LUTHERAN WARNING.] Luther in fact was never Zwinglian as regards the Communion. Far from that, in 1519, he still believed in Transubstantiation. Why then should he speak of a sign? It was for this reason. While, according to Zwingle, the bread and wine are signs of the body and blood of Christ, according to Luther, the very body and blood of Jesus Christ are signs of God's grace. These opinions are widely different from one another. Erelong this disagreement declared itself. In 1527 Zwingle in his _Friendly Exposition_[189] repeated Luther's opinion with mildness and respect. Unfortunately the pamphlet of the Saxon Reformer "against the enthusiasts" was then issuing from the press, and in it Luther expressed his indignation that his adversaries should dare to speak of christian unity and peace. "Well!" exclaimed he, "since they thus insult all reason, I will give them a Lutheran warning.[190] Cursed be this concord! cursed be this charity! down, down with it, to the bottomless pit of hell! If I should murder your father, your mother, your wife, your child, and then, wishing to murder you, I should say to you, Let us be at peace, my dear friend! what answer would you make?--It is thus that the enthusiasts who murder Jesus Christ my Lord, God the Father, and Christendom my mother, wish to murder me also; and then they say, Let us be friends!" [189] _Amica exegesis_, id est, Expositio Eucharistæ negotii ad M. Lutherum.--(Zw. Opp.) [190] Eine Lutherische Warnung.--(L. Opp. xix. p. 391. Wider die Schwärmgeister.) Zwingle wrote two replies "to the excellent Martin Luther," in a cold tone and with a haughty calmness more difficult to pardon than the invectives of the Saxon doctor. "We ought to esteem you a vessel of honour, and we do so with joy," said he, "notwithstanding your faults." Pamphlet followed pamphlet, Luther always writing with the same impetuosity, and Zwingle with the same coolness and irony. [Sidenote: PROPOSED CONFERENCE AT MARBURG.]