“Offeras transfigurandum altaribus.” The Benedictine Editors, by a curious anachronism, see here a reference to transubstantiation. But μεταποίησις, the word translated “transformation” implies no more than the being made to undergo a change, which may be a change in dignity without involving a change of substance. cf. pp. 200 and 201, where Orthodoxus distinctly asserts that the substance remains unchanged. Transubstantiation, definitely declared an article of faith in 1215, seems to have been first taught early in the 9th c. Vide Bp. Harold Browne on Art. xxviii.