The subject of the deepest importance to Luther in this treatise was the sacrament of the altar. He dwells on the mutilated form, without the cup, in which the Lord's Supper was given to the laity; on the doctrine invented about the change of the bread, instead of keeping to the simple word of Scripture; and, lastly, on the substitution of a sacrifice, supposed to be offered to God by the priest, for the institution ordained by Christ for the nourishment of the faithful. The withholding of the cup he calls an act of ungodliness and tyranny, beyond the power of either Pope or Council to prescribe. Against the sacrifice of the mass he had published just before a sermon in German. He was well aware that his principles involved, as indeed he intended, a revolution of the whole service, and an attack on an ordinance, upon which a number of other abuses, of great importance to the hierarchy, depended. But he ventured it, because God's word obliged him to do it. So now he proceeds to describe, in contrast to this mass, the one of true Christian institution, and resting wholly, as he conceived it, on the words of Christ, when instituting the Last Supper, 'Take, and eat,' etc. Christ would here say, 'See, thou poor sinner, out of pure love I promise to thee, before thou canst either earn or promise anything, forgiveness of all thy sins, and eternal life, and to assure thee of this I give here my Body and shed my Blood; do thou, by my death, rest assured of this promise, and take as a sign my Body and my Blood.' For the worthy celebration of this mass, nothing is required but faith, which shall trust securely in this promise; with this faith will come the sweetest stirrings of the heart, which will unfold itself in love, and yearn for the good Saviour, and in Him will become a new creature. As regards baptism Luther lamented that it was no longer allowed to possess the true significance and value it ought to have for a man's whole life. Whereas in truth the person baptized received a promise of mercy from God, to which time after time, even from the sins of his future life, he might and was bound to turn, it was taught, that in sinning after baptism, the Christian was like a shipwrecked man, who, instead of the ship, could only reach a plank; this being the sacrament of penance, with its accompanying outward formalities. Whereas further, in true baptism he had vowed to dedicate his whole life and conduct to God, other vows of human invention were now demanded of him. Whereas he then became a full partaker of Christian liberty, he was now burdened with ordinances of the Church, devised by man.