See also: Scrinium/Consecration
Luther (WA 38:299): Nostra autem sententia est Corpus ita cum pane seu in pane esse, Vt reuera cum pane manducetur, et quemcunque motum vel actionem panis habet, eandem et corpus Christi, vt Corpus Christi vere dicatur ferri, dari, accipi, manducari, quando panis fertur, datur, accipitur, manducatur. idest: Hoc est corpus Meum. (But our opinion is that the body is with or in the bread in such a way that it is really eaten with the bread; and whatever movement or action the bread has, so does the body of Christ so that one may truly say that the body of Christ is carried, given, received, and eaten when the bread is carried, given, received, and eaten—that is to say: “This is My body.”)
Nevertheless, under the form of bread, the true body of Christ, given for us on the cross, under the form of wine, the true blood of Christ, shed for us, are present; furthermore, it is not a spiritual or imagined body and blood but the genuine natural body and blood derived from the holy, virginal, true, human body of Mary, conceived without a human body by the Holy Spirit alone. This body and blood of Christ are even now sitting at the right hand of God in majesty, in the divine person called Jesus Christ, who is a genuine, true, eternal God with the Father of whom he was born from eternity, etc. This body and this blood of the Son of God, Jesus Christ, not only the holy and worthy but also sinners and the unworthy truly administer and receive bodily, although invisibly, with their hands, their mouths, the chalice, paten, corporal, and whatever they use for this purpose when it is administered and received in the mass.—Martin Luther, Letter of Martin Luther Concerning His Book on the Private Mass