3. Scotus’ own Opinion

382. Accordingly, then, one must hold that it is not of the necessity of the consecratable bread either that it be unleavened or that it be leavened, because according to Anselm, Letter on the Sacrifice of Leavened and Unleavened ch.1, “leavened and unleavened do not differ in substance.” And therefore we do not deny that the Greeks truly confect [the sacrament].

383. This is also plain because, at the time of Leo IX, it was established that the sacrament would be confected with leavened bread. But this was for a time, so that the heresy of the Ebionites might be extinguished, who said that it was necessary for Christians to Judaize, and as a result they confected their pasch with unleavened bread, as the Jews did; and consecration with leavened bread was ordained for extinction of this heresy. But afterwards, when the heresy was extinct, the Western Church returned to its first custom, which was in conformity with the institution of Christ and the promulgation made through his vicar, St. Peter.

384. But today it is of the necessity of the minister, at least in the Latin Church, to confect with unleavened bread, as was said above in the second conclusion of this distinction [n.379, cf. nn.140-141]. And perhaps too the Greeks sin gravely who do not conform themselves to the Church of Peter, especially since here the solid foundation is held, because Christ did thus institute the celebrating of this sacrament. At least, although it is not necessary that it could not be done differently, yet thus is it more fittingly celebrated.